This section only describes the rules for text/html resources. Rules for XML resources are
discussed in the section below entitled "The XHTML
syntax".
This section only applies to documents, authoring tools, and markup generators. In particular, it does not apply to conformance checkers; conformance checkers must use the requirements given in the next section ("parsing HTML documents").
Documents must consist of the following parts, in the given order:
html element.The various types of content mentioned above are described in the next few sections.
In addition, there are some restrictions on how character encoding declarations are to be serialized, as discussed in the section on that topic.
Space characters before the root html element, and
space characters at the start of the html element and
before the head element, will be dropped when the
document is parsed; space characters after the root
html element will be parsed as if they were at the end
of the body element. Thus, space characters around the
root element do not round-trip.
It is suggested that newlines be inserted after the DOCTYPE,
after any comments that are before the root element, after the
html element's start tag (if it is not omitted), and after any comments
that are inside the html element but before the
head element.
Many strings in the HTML syntax (e.g. the names of elements and their attributes) are case-insensitive, but only for characters in the ranges U+0041 .. U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) and U+0061 .. U+007A (LATIN SMALL LETTER A to LATIN SMALL LETTER Z). For convenience, in this section this is just referred to as "case-insensitive".
A DOCTYPE is a mostly useless, but required, header.
DOCTYPEs are required for legacy reasons. When omitted, browsers tend to use a different rendering mode that is incompatible with some specifications. Including the DOCTYPE in a document ensures that the browser makes a best-effort attempt at following the relevant specifications.
A DOCTYPE must consist of the following characters, in this order:
<) character.!) character.DOCTYPE".HTML".>) character.In other words, <!DOCTYPE HTML>,
case-insensitively.
For the purposes of HTML generators that cannot output HTML
markup with the short DOCTYPE "<!DOCTYPE
HTML>", a DOCTYPE legacy string may be inserted
into the DOCTYPE (in the position defined above). This string must
consist of:
SYSTEM".about:legacy-compat".In other words, <!DOCTYPE HTML SYSTEM
"about:legacy-compat"> or <!DOCTYPE HTML SYSTEM
'about:legacy-compat'>, case-insensitively except for the bit
in quotes.
The DOCTYPE legacy string should not be used unless the document is generated from a system that cannot output the shorter string.
There are five different kinds of elements: void elements, CDATA elements, RCDATA elements, foreign elements, and normal elements.
area, base, br,
col, command, embed,
hr, img, input,
keygen, link, meta,
param, sourcescript, styletextarea, titleTags are used to delimit the start and end of elements in the markup. CDATA, RCDATA, and normal elements have a start tag to indicate where they begin, and an end tag to indicate where they end. The start and end tags of certain normal elements can be omitted, as described later. Those that cannot be omitted must not be omitted. Void elements only have a start tag; end tags must not be specified for void elements. Foreign elements must either have a start tag and an end tag, or a start tag that is marked as self-closing, in which case they must not have an end tag.
The contents of the element must be placed between just after the start tag (which might be implied, in certain cases) and just before the end tag (which again, might be implied in certain cases). The exact allowed contents of each individual element depends on the content model of that element, as described earlier in this specification. Elements must not contain content that their content model disallows. In addition to the restrictions placed on the contents by those content models, however, the five types of elements have additional syntactic requirements.
Void elements can't have any contents (since there's no end tag, no content can be put between the start tag and the end tag).
CDATA elements can have text, though it has restrictions described below.
RCDATA elements can have text and character references, but the text must not contain an ambiguous ampersand. There are also further restrictions described below.
Foreign elements whose start tag is marked as self-closing can't
have any contents (since, again, as there's no end tag, no content
can be put between the start tag and the end tag). Foreign elements
whose start tag is not marked as self-closing can have
text, character references, CDATA sections, other elements, and comments, but the text must not
contain the character U+003C LESS-THAN SIGN (<) or
an ambiguous
ampersand.
Normal elements can have text,
character references, other
elements, and comments, but the text must not
contain the character U+003C LESS-THAN SIGN (<) or
an ambiguous
ampersand. Some normal elements also have yet more restrictions on what
content they are allowed to hold, beyond the restrictions imposed by
the content model and those described in this paragraph. Those
restrictions are described below.
Tags contain a tag name,
giving the element's name. HTML elements all have names that only
use characters in the range U+0030 DIGIT ZERO .. U+0039 DIGIT NINE,
U+0061 LATIN SMALL LETTER A .. U+007A LATIN SMALL LETTER Z, U+0041
LATIN CAPITAL LETTER A .. U+005A LATIN CAPITAL LETTER Z, and U+002D
HYPHEN-MINUS (-). In the HTML syntax, tag names may be
written with any mix of lower- and uppercase letters that, when
converted to all-lowercase, matches the element's tag name; tag
names are case-insensitive.
Start tags must have the following format:
<)./) character. This character has no
effect on void elements, but on foreign elements it marks the start
tag as self-closing.>) character.End tags must have the following format:
<)./).>) character.Attributes for an element are expressed inside the element's start tag.
Attributes have a name and a value. Attribute names must consist of one or more characters other than the space characters, U+0000 NULL, U+0022 QUOTATION MARK ("), U+0027 APOSTROPHE ('), U+003E GREATER-THAN SIGN (>), U+002F SOLIDUS (/), and U+003D EQUALS SIGN (=) characters, the control characters, and any characters that are not defined by Unicode. In the HTML syntax, attribute names may be written with any mix of lower- and uppercase letters that are an ASCII case-insensitive match for the attribute's name.
Attribute values are a mixture of text and character references, except with the additional restriction that the text cannot contain an ambiguous ampersand.
Attributes can be specified in four different ways:
Just the attribute name.
In the following example, the disabled attribute is given with
the empty attribute syntax:
<input disabled>
If an attribute using the empty attribute syntax is to be followed by another attribute, then there must be a space character separating the two.
The attribute name,
followed by zero or more space
characters, followed by a single U+003D EQUALS SIGN
character, followed by zero or more space characters, followed by the attribute value, which, in
addition to the requirements given above for attribute values,
must not contain any literal space
characters, any U+0022 QUOTATION MARK (")
characters, U+0027 APOSTROPHE (') characters,
U+003D EQUALS SIGN (=) characters, or U+003E
GREATER-THAN SIGN (>) characters, and must not be
the empty string.
In the following example, the value attribute is given
with the unquoted attribute value syntax:
<input value=yes>
If an attribute using the unquoted attribute syntax is to be
followed by another attribute or by one of the optional U+002F
SOLIDUS (/) characters allowed in step 6 of the start tag syntax above, then there
must be a space character separating the two.
The attribute name,
followed by zero or more space
characters, followed by a single U+003D EQUALS SIGN
character, followed by zero or more space characters, followed by a single U+0027
APOSTROPHE (') character, followed by the attribute value, which, in
addition to the requirements given above for attribute values,
must not contain any literal U+0027 APOSTROPHE (')
characters, and finally followed by a second single U+0027
APOSTROPHE (') character.
In the following example, the type attribute is given with the
single-quoted attribute value syntax:
<input type='checkbox'>
If an attribute using the single-quoted attribute syntax is to be followed by another attribute, then there must be a space character separating the two.
The attribute name,
followed by zero or more space
characters, followed by a single U+003D EQUALS SIGN
character, followed by zero or more space characters, followed by a single U+0022
QUOTATION MARK (") character, followed by the attribute value, which, in
addition to the requirements given above for attribute values,
must not contain any literal U+0022 QUOTATION MARK
(") characters, and finally followed by a second
single U+0022 QUOTATION MARK (") character.
In the following example, the name attribute is given with the
double-quoted attribute value syntax:
<input name="be evil">
If an attribute using the double-quoted attribute syntax is to be followed by another attribute, then there must be a space character separating the two.
There must never be two or more attributes on the same start tag whose names are an ASCII case-insensitive match for each other.
Certain tags can be omitted.
Omitting an element's start tag does not mean the element
is not present; it is implied, but it is still there. An HTML
document always has a root html element, even if the
string <html> doesn't appear anywhere in
the markup.
An html element's start tag may be omitted if the
first thing inside the html element is not a comment.
An html element's end
tag may be omitted if the html element is not
immediately followed by a comment.
A head element's start tag may be omitted if the first thing inside the
head element is an element.
A head element's end
tag may be omitted if the head element is not
immediately followed by a space character or a comment.
A body element's start tag may be omitted if the
element is empty, or if the first thing inside the body
element is not a space character or a comment, except if the first thing
inside the body element is a script or
style element.
A body element's end
tag may be omitted if the body element is not
immediately followed by a comment.
A li element's end
tag may be omitted if the li element is
immediately followed by another li element or if there
is no more content in the parent element.
A dt element's end
tag may be omitted if the dt element is
immediately followed by another dt element or a
dd element.
A dd element's end
tag may be omitted if the dd element is
immediately followed by another dd element or a
dt element, or if there is no more content in the
parent element.
A p element's end
tag may be omitted if the p element is
immediately followed by an address,
article, aside, blockquote,
datagrid, dialog, dir,
div, dl, fieldset,
footer, form, h1,
h2, h3, h4, h5,
h6, header, hr,
menu, nav, ol,
p, pre, section,
table, or ul, element, or if there is no
more content in the parent element and the parent element is not an
a element.
An rt element's end
tag may be omitted if the rt element is
immediately followed by an rt or rp
element, or if there is no more content in the parent element.
An rp element's end
tag may be omitted if the rp element is
immediately followed by an rt or rp
element, or if there is no more content in the parent element.
An optgroup element's end tag may be omitted if the
optgroup element is immediately followed by
another optgroup element, or if there is no
more content in the parent element.
An option element's end
tag may be omitted if the option element is
immediately followed by another option element, or if
it is immediately followed by an optgroup element, or
if there is no more content in the parent element.
A colgroup element's start tag may be omitted if the
first thing inside the colgroup element is a
col element, and if the element is not immediately
preceded by another colgroup element whose end tag has been omitted. (It can't be
omitted if the element is empty.)
A colgroup element's end tag may be omitted if the
colgroup element is not immediately followed by a
space character or a comment.
A thead element's end
tag may be omitted if the thead element is
immediately followed by a tbody or tfoot
element.
A tbody element's start tag may be omitted if the
first thing inside the tbody element is a
tr element, and if the element is not immediately
preceded by a tbody, thead, or
tfoot element whose end
tag has been omitted. (It can't be omitted if the element is
empty.)
A tbody element's end
tag may be omitted if the tbody element is
immediately followed by a tbody or tfoot
element, or if there is no more content in the parent element.
A tfoot element's end
tag may be omitted if the tfoot element is
immediately followed by a tbody element, or if there is
no more content in the parent element.
A tr element's end
tag may be omitted if the tr element is
immediately followed by another tr element, or if there
is no more content in the parent element.
A td element's end
tag may be omitted if the td element is
immediately followed by a td or th
element, or if there is no more content in the parent element.
A th element's end
tag may be omitted if the th element is
immediately followed by a td or th
element, or if there is no more content in the parent element.
However, a start tag must never be omitted if it has any attributes.
For historical reasons, certain elements have extra restrictions beyond even the restrictions given by their content model.
A table element must not contain tr
elements, even though these elements are technically allowed inside
table elements according to the content models
described in this specification. (If a tr element is
put inside a table in the markup, it will in fact imply
a tbody start tag before it.)
A single U+000A LINE FEED (LF) character may be placed
immediately after the start
tag of pre and textarea
elements. This does not affect the processing of the element. The
otherwise optional U+000A LINE FEED (LF) character must be
included if the element's contents start with that character
(because otherwise the leading newline in the contents would be
treated like the optional newline, and ignored).
The text in CDATA and RCDATA elements must not contain any
occurrences of the string "</" (U+003C
LESS-THAN SIGN, U+002F SOLIDUS) followed by characters that
case-insensitively match the tag name of the element followed by one
of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM
FEED (FF), U+0020 SPACE, U+003E GREATER-THAN SIGN (>), or U+002F
SOLIDUS (/), unless that string is part of an escaping text span.
An escaping text span is a span of text that starts with an escaping text span start that is not itself in an escaping text span, and ends at the next escaping text span end. There cannot be any character references inside an escaping text span — sequences of characters that would look like character references do not have special meaning.
An escaping text span
start is a part of text that
consists of the four character sequence "<!--" (U+003C LESS-THAN SIGN, U+0021 EXCLAMATION
MARK, U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS).
An escaping text span end is
a part of text that consists of the
three character sequence "-->" (U+002D
HYPHEN-MINUS, U+002D HYPHEN-MINUS, U+003E GREATER-THAN SIGN) whose
U+003E GREATER-THAN SIGN (>).
An escaping text span start may share its U+002D HYPHEN-MINUS characters with its corresponding escaping text span end.
The text in CDATA and RCDATA elements must not have an escaping text span start that is not followed by an escaping text span end.
Text is allowed inside elements, attributes, and comments. Text must consist of Unicode characters. Text must not contain U+0000 characters. Text must not contain permanently undefined Unicode characters. Text must not contain control characters other than space characters. Extra constraints are placed on what is and what is not allowed in text based on where the text is to be put, as described in the other sections.
Newlines in HTML may be represented either as U+000D CARRIAGE RETURN (CR) characters, U+000A LINE FEED (LF) characters, or pairs of U+000D CARRIAGE RETURN (CR), U+000A LINE FEED (LF) characters in that order.
In certain cases described in other sections, text may be mixed with character references. These can be used to escape characters that couldn't otherwise legally be included in text.
Character references must start with a U+0026 AMPERSAND
(&). Following this, there are three possible kinds
of character references:
;) character.#) character, followed by one or more digits in the
range U+0030 DIGIT ZERO .. U+0039 DIGIT NINE, representing a
base-ten integer that itself is a Unicode code point that is
not U+0000, U+000D, in the range U+0080 .. U+009F, or in the range
0xD800 .. 0xDFFF (surrogates). The digits must then be followed by
a U+003B SEMICOLON character (;).#) character, which must be followed by either a
U+0078 LATIN SMALL LETTER X or a U+0058 LATIN CAPITAL LETTER X
character, which must then be followed by one or more digits in the
range U+0030 DIGIT ZERO .. U+0039 DIGIT NINE, U+0061 LATIN SMALL
LETTER A .. U+0066 LATIN SMALL LETTER F, and U+0041 LATIN CAPITAL
LETTER A .. U+0046 LATIN CAPITAL LETTER F, representing a
base-sixteen integer that itself is a Unicode code point that is
not U+0000, U+000D, in the range U+0080 .. U+009F, or in the range
0xD800 .. 0xDFFF (surrogates). The digits must then be followed by
a U+003B SEMICOLON character (;).An ambiguous
ampersand is a U+0026 AMPERSAND (&) character
that is followed by some text other
than a space character, a U+003C LESS-THAN SIGN
character ('<'), or another U+0026 AMPERSAND (&)
character.
CDATA sections must start with
the character sequence U+003C LESS-THAN SIGN, U+0021 EXCLAMATION
MARK, U+005B LEFT SQUARE BRACKET, U+0043 LATIN CAPITAL LETTER C,
U+0044 LATIN CAPITAL LETTER D, U+0041 LATIN CAPITAL LETTER A, U+0054
LATIN CAPITAL LETTER T, U+0041 LATIN CAPITAL LETTER A, U+005B LEFT
SQUARE BRACKET (<![CDATA[). Following this
sequence, the CDATA section may have text, with the additional restriction
that the text must not contain the three character sequence U+005D
RIGHT SQUARE BRACKET, U+005D RIGHT SQUARE BRACKET, U+003E
GREATER-THAN SIGN (]]>). Finally, the CDATA
section must be ended by the three character sequence U+005D RIGHT
SQUARE BRACKET, U+005D RIGHT SQUARE BRACKET, U+003E GREATER-THAN
SIGN (]]>).
Comments must start with the
four character sequence U+003C LESS-THAN SIGN, U+0021 EXCLAMATION
MARK, U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS (<!--). Following this sequence, the comment may
have text, with the additional
restriction that the text must not start with a single U+003E
GREATER-THAN SIGN ('>') character, nor start with a U+002D
HYPHEN-MINUS (-) character followed by a
U+003E GREATER-THAN SIGN ('>') character, nor contain two
consecutive U+002D HYPHEN-MINUS (-)
characters, nor end with a U+002D HYPHEN-MINUS (-) character. Finally, the comment must be ended by
the three character sequence U+002D HYPHEN-MINUS, U+002D
HYPHEN-MINUS, U+003E GREATER-THAN SIGN (-->).
This section only applies to user agents, data mining tools, and conformance checkers.
The rules for parsing XML documents (and thus XHTML documents) into DOM trees are covered by the next section, entitled "The XHTML syntax".
For HTML documents, user agents must use the parsing rules described in this section to generate the DOM trees. Together, these rules define what is referred to as the HTML parser.
While the HTML form of HTML5 bears a close resemblance to SGML and XML, it is a separate language with its own parsing rules.
Some earlier versions of HTML (in particular from HTML2 to HTML4) were based on SGML and used SGML parsing rules. However, few (if any) web browsers ever implemented true SGML parsing for HTML documents; the only user agents to strictly handle HTML as an SGML application have historically been validators. The resulting confusion — with validators claiming documents to have one representation while widely deployed Web browsers interoperably implemented a different representation — has wasted decades of productivity. This version of HTML thus returns to a non-SGML basis.
Authors interested in using SGML tools in their authoring pipeline are encouraged to use XML tools and the XML serialization of HTML5.
This specification defines the parsing rules for HTML documents, whether they are syntactically correct or not. Certain points in the parsing algorithm are said to be parse errors. The error handling for parse errors is well-defined: user agents must either act as described below when encountering such problems, or must abort processing at the first error that they encounter for which they do not wish to apply the rules described below.
Conformance checkers must report at least one parse error condition to the user if one or more parse error conditions exist in the document and must not report parse error conditions if none exist in the document. Conformance checkers may report more than one parse error condition if more than one parse error conditions exist in the document. Conformance checkers are not required to recover from parse errors.
Parse errors are only errors with the syntax of HTML. In addition to checking for parse errors, conformance checkers will also verify that the document obeys all the other conformance requirements described in this specification.
The input to the HTML parsing process consists of a stream of
Unicode characters, which is passed through a
tokenization stage (lexical analysis) followed by a
tree construction stage (semantic analysis). The output
is a Document object.
Implementations that do not
support scripting do not have to actually create a DOM
Document object, but the DOM tree in such cases is
still used as the model for the rest of the specification.
In the common case, the data handled by the tokenization stage
comes from the network, but it can also come from script, e.g. using the document.write() API.
There is only one set of states for the tokenizer stage and the tree construction stage, but the tree construction stage is reentrant, meaning that while the tree construction stage is handling one token, the tokenizer might be resumed, causing further tokens to be emitted and processed before the first token's processing is complete.
In the following example, the tree construction stage will be called upon to handle a "p" start tag token while handling the "script" start tag token:
...
<script>
document.write('<p>');
</script>
...
To handle these cases, parsers have a script nesting level, which must be initially set to zero, and a parser pause flag, which must be initially set to false.
The stream of Unicode characters that comprises the input to the tokenization stage will be initially seen by the user agent as a stream of bytes (typically coming over the network or from the local file system). The bytes encode the actual characters according to a particular character encoding, which the user agent must use to decode the bytes into characters.
For XML documents, the algorithm user agents must use to determine the character encoding is given by the XML specification. This section does not apply to XML documents. [XML]
In some cases, it might be impractical to unambiguously determine the encoding before parsing the document. Because of this, this specification provides for a two-pass mechanism with an optional pre-scan. Implementations are allowed, as described below, to apply a simplified parsing algorithm to whatever bytes they have available before beginning to parse the document. Then, the real parser is started, using a tentative encoding derived from this pre-parse and other out-of-band metadata. If, while the document is being loaded, the user agent discovers an encoding declaration that conflicts with this information, then the parser can get reinvoked to perform a parse of the document with the real encoding.
User agents must use the following algorithm (the encoding sniffing algorithm) to determine the character encoding to use when decoding a document in the first pass. This algorithm takes as input any out-of-band metadata available to the user agent (e.g. the Content-Type metadata of the document) and all the bytes available so far, and returns an encoding and a confidence. The confidence is either tentative, certain, or irrelevant. The encoding used, and whether the confidence in that encoding is tentative or confident, is used during the parsing to determine whether to change the encoding. If no encoding is necessary, e.g. because the parser is operating on a stream of Unicode characters and doesn't have to use an encoding at all, then the confidence is irrelevant.
If the transport layer specifies an encoding, and it is supported, return that encoding with the confidence certain, and abort these steps.
The user agent may wait for more bytes of the resource to be available, either in this step or at any later step in this algorithm. For instance, a user agent might wait 500ms or 512 bytes, whichever came first. In general preparsing the source to find the encoding improves performance, as it reduces the need to throw away the data structures used when parsing upon finding the encoding information. However, if the user agent delays too long to obtain data to determine the encoding, then the cost of the delay could outweigh any performance improvements from the preparse.
For each of the rows in the following table, starting with the first one and going down, if there are as many or more bytes available than the number of bytes in the first column, and the first bytes of the file match the bytes given in the first column, then return the encoding given in the cell in the second column of that row, with the confidence certain, and abort these steps:
| Bytes in Hexadecimal | Encoding |
|---|---|
| FE FF | UTF-16BE |
| FF FE | UTF-16LE |
| EF BB BF | UTF-8 |
This step looks for Unicode Byte Order Marks (BOMs).
Otherwise, the user agent will have to search for explicit character encoding information in the file itself. This should proceed as follows:
Let position be a pointer to a byte in the input stream, initially pointing at the first byte. If at any point during these substeps the user agent either runs out of bytes or decides that scanning further bytes would not be efficient, then skip to the next step of the overall character encoding detection algorithm. User agents may decide that scanning any bytes is not efficient, in which case these substeps are entirely skipped.
Now, repeat the following "two" steps until the algorithm aborts (either because user agent aborts, as described above, or because a character encoding is found):
If position points to:
Advance the position pointer so that it points at the first 0x3E byte which is preceded by two 0x2D bytes (i.e. at the end of an ASCII '-->' sequence) and comes after the 0x3C byte that was found. (The two 0x2D bytes can be the same as the those in the '<!--' sequence.)
Advance the position pointer so that it points at the next 0x09, 0x0A, 0x0C, 0x0D, 0x20, or 0x2F byte (the one in sequence of characters matched above).
Get an attribute and its value. If no attribute was sniffed, then skip this inner set of steps, and jump to the second step in the overall "two step" algorithm.
If the attribute's name is neither "charset" nor "content",
then return to step 2 in these inner steps.
If the attribute's name is "charset", let charset be
the attribute's value, interpreted as a character
encoding.
Otherwise, the attribute's name is "content": apply the algorithm for
extracting an encoding from a Content-Type, giving the
attribute's value as the string to parse. If an encoding is
returned, let charset be that
encoding. Otherwise, return to step 2 in these inner
steps.
If charset is a UTF-16 encoding, change it to UTF-8.
If charset is a supported character encoding, then return the given encoding, with confidence tentative, and abort all these steps.
Otherwise, return to step 2 in these inner steps.
Advance the position pointer so that it points at the next 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), 0x20 (ASCII space), or 0x3E (ASCII '>') byte.
Repeatedly get an attribute until no further attributes can be found, then jump to the second step in the overall "two step" algorithm.
Advance the position pointer so that it points at the first 0x3E byte (ASCII '>') that comes after the 0x3C byte that was found.
Do nothing with that byte.
When the above "two step" algorithm says to get an attribute, it means doing this:
If the byte at position is one of 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), 0x20 (ASCII space), or 0x2F (ASCII '/') then advance position to the next byte and redo this substep.
If the byte at position is 0x3E (ASCII '>'), then abort the "get an attribute" algorithm. There isn't one.
Otherwise, the byte at position is the start of the attribute name. Let attribute name and attribute value be the empty string.
Attribute name: Process the byte at position as follows:
Advance position to the next byte and return to the previous step.
Spaces. If the byte at position is one of 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), or 0x20 (ASCII space) then advance position to the next byte, then, repeat this step.
If the byte at position is not 0x3D (ASCII '='), abort the "get an attribute" algorithm. The attribute's name is the value of attribute name, its value is the empty string.
Advance position past the 0x3D (ASCII '=') byte.
Value. If the byte at position is one of 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), or 0x20 (ASCII space) then advance position to the next byte, then, repeat this step.
Process the byte at position as follows:
Process the byte at position as follows:
Advance position to the next byte and return to the previous step.
For the sake of interoperability, user agents should not use a pre-scan algorithm that returns different results than the one described above. (But, if you do, please at least let us know, so that we can improve this algorithm and benefit everyone...)
If the user agent has information on the likely encoding for this page, e.g. based on the encoding of the page when it was last visited, then return that encoding, with the confidence tentative, and abort these steps.
The user agent may attempt to autodetect the character encoding from applying frequency analysis or other algorithms to the data stream. If autodetection succeeds in determining a character encoding, then return that encoding, with the confidence tentative, and abort these steps. [UNIVCHARDET]
Otherwise, return an implementation-defined or
user-specified default character encoding, with the confidence
tentative. In non-legacy environments, the more
comprehensive UTF-8 encoding is
recommended. Due to its use in legacy content, windows-1252 is recommended as a default in
predominantly Western demographics instead. Since these encodings
can in many cases be distinguished by inspection, a user agent may
heuristically decide which to use as a default.
The document's character encoding must immediately be set to the value returned from this algorithm, at the same time as the user agent uses the returned value to select the decoder to use for the input stream.
Given an encoding, the bytes in the input stream must be converted to Unicode characters for the tokenizer, as described by the rules for that encoding, except that the leading U+FEFF BYTE ORDER MARK character, if any, must not be stripped by the encoding layer (it is stripped by the rule below).
Bytes or sequences of bytes in the original byte stream that could not be converted to Unicode characters must be converted to U+FFFD REPLACEMENT CHARACTER code points.
Bytes or sequences of bytes in the original byte stream that did not conform to the encoding specification (e.g. invalid UTF-8 byte sequences in a UTF-8 input stream) are errors that conformance checkers are expected to report.
Any byte or sequences of bytes in the original byte stream that is misinterpreted for compatibility is a parse error.
One leading U+FEFF BYTE ORDER MARK character must be ignored if any are present.
All U+0000 NULL characters in the input must be replaced by U+FFFD REPLACEMENT CHARACTERs. Any occurrences of such characters is a parse error.
Any occurrences of any characters in the ranges U+0001 to U+0008, U+000E to U+001F, U+007F to U+009F, U+D800 to U+DFFF, U+FDD0 to U+FDEF, and characters U+000B, U+FFFE, U+FFFF, U+1FFFE, U+1FFFF, U+2FFFE, U+2FFFF, U+3FFFE, U+3FFFF, U+4FFFE, U+4FFFF, U+5FFFE, U+5FFFF, U+6FFFE, U+6FFFF, U+7FFFE, U+7FFFF, U+8FFFE, U+8FFFF, U+9FFFE, U+9FFFF, U+AFFFE, U+AFFFF, U+BFFFE, U+BFFFF, U+CFFFE, U+CFFFF, U+DFFFE, U+DFFFF, U+EFFFE, U+EFFFF, U+FFFFE, U+FFFFF, U+10FFFE, and U+10FFFF are parse errors. (These are all control characters or permanently undefined Unicode characters.)
U+000D CARRIAGE RETURN (CR) characters and U+000A LINE FEED (LF) characters are treated specially. Any CR characters that are followed by LF characters must be removed, and any CR characters not followed by LF characters must be converted to LF characters. Thus, newlines in HTML DOMs are represented by LF characters, and there are never any CR characters in the input to the tokenization stage.
The next input character is the first character in the input stream that has not yet been consumed. Initially, the next input character is the first character in the input. The current input character is the last character to have been consumed.
The insertion point is the position (just before a
character or just before the end of the input stream) where content
inserted using document.write() is actually
inserted. The insertion point is relative to the position of the
character immediately after it, it is not an absolute offset into
the input stream. Initially, the insertion point is
uninitialized.
The "EOF" character in the tables below is a conceptual character
representing the end of the input stream. If the parser
is a script-created parser, then the end of the
input stream is reached when an explicit "EOF"
character (inserted by the document.close() method) is
consumed. Otherwise, the "EOF" character is not a real character in
the stream, but rather the lack of any further characters.
When the parser requires the user agent to change the encoding, it must run the following steps. This might happen if the encoding sniffing algorithm described above failed to find an encoding, or if it found an encoding that was not the actual encoding of the file.
The insertion mode is a flag that controls the primary operation of the tree construction stage.
Initially, the insertion mode is "initial". It can change to "before html", "before head", "in head", "in head noscript", "after head", "in body", "in CDATA/RCDATA", "in table", "in caption", "in column group", "in table body", "in row", "in cell", "in select", "in select in table", "in foreign content", "after body", "in frameset", "after frameset", "after after body", and "after after frameset" during the course of the parsing, as described in the tree construction stage. The insertion mode affects how tokens are processed and whether CDATA sections are supported.
Seven of these modes, namely "in head", "in body", "in CDATA/RCDATA", "in table", "in table body", "in row", "in cell", and "in select", are special, in that the other modes defer to them at various times. When the algorithm below says that the user agent is to do something "using the rules for the m insertion mode", where m is one of these modes, the user agent must use the rules described under the m insertion mode's section, but must leave the insertion mode unchanged unless the rules in m themselves switch the insertion mode to a new value.
When the insertion mode is switched to "in CDATA/RCDATA", the original insertion mode is also set. This is the insertion mode to which the tree construction stage will return when the corresponding end tag is parsed.
When the insertion mode is switched to "in foreign content", the secondary insertion mode is also set. This secondary mode is used within the rules for the "in foreign content" mode to handle HTML (i.e. not foreign) content.
When the steps below require the UA to reset the insertion mode appropriately, it means the UA must follow these steps:
select element,
then switch the insertion mode to "in select" and abort these
steps. (fragment case)td or
th element and last is false, then
switch the insertion mode to "in cell" and abort these steps.tr element, then
switch the insertion mode to "in row" and abort these steps.tbody,
thead, or tfoot element, then switch the
insertion mode to "in table body" and abort these steps.caption element,
then switch the insertion mode to "in caption" and abort
these steps.colgroup element,
then switch the insertion mode to "in column group" and
abort these steps. (fragment case)table element,
then switch the insertion mode to "in table" and abort these
steps.head element,
then switch the insertion mode to "in body" ("in body"! not "in head"!) and abort
these steps. (fragment case)body element,
then switch the insertion mode to "in body" and abort these
steps.frameset element,
then switch the insertion mode to "in frameset" and abort
these steps. (fragment case)html element,
then: if the head element
pointer is null, switch the insertion mode to
"before head",
otherwise, switch the insertion mode to "after head". In either
case, abort these steps. (fragment case)Initially, the stack of open elements is empty. The stack grows downwards; the topmost node on the stack is the first one added to the stack, and the bottommost node of the stack is the most recently added node in the stack (notwithstanding when the stack is manipulated in a random access fashion as part of the handling for misnested tags).
The "before
html" insertion mode creates the
html root element node, which is then added to the
stack.
In the fragment case, the stack of open
elements is initialized to contain an html
element that is created as part of that algorithm. (The fragment
case skips the "before html" insertion mode.)
The html node, however it is created, is the topmost
node of the stack. It never gets popped off the stack.
The current node is the bottommost node in this stack.
The current table is the last table
element in the stack of open elements, if there is
one. If there is no table element in the stack of
open elements (fragment case), then the
current table is the first element in the stack
of open elements (the html element).
Elements in the stack fall into the following categories:
The following HTML elements have varying levels of special
parsing rules: address, area,
article, aside, base,
basefont, bgsound,
blockquote, body, br,
center, col, colgroup,
command, datagrid, dd,
details, dialog, dir,
div, dl, dt,
embed, fieldset, figure,
footer, form, frame,
frameset, h1, h2,
h3, h4, h5, h6,
head, header, hr,
iframe, img, input,
isindex, li, link,
listing, menu, meta,
nav, noembed, noframes,
noscript, ol, p,
param, plaintext, pre,
script, section, select,
spacer, style, tbody,
textarea, tfoot, thead,
title, tr, ul, and
wbr.
The following HTML elements introduce new scopes for various parts of the
parsing: applet, button,
caption, html, marquee,
object, table, td,
th, and SVG's foreignObject.
The following HTML elements are those that end up in the
list of active formatting elements: a,
b, big, code,
em, font, i,
nobr, s, small,
strike, strong, tt, and
u.
All other elements found while parsing an HTML document.
The stack of open elements is said to have an element in scope when the following algorithm terminates in a match state:
Initialize node to be the current node (the bottommost node of the stack).
If node is the target node, terminate in a match state.
Otherwise, if node is one of the following elements, terminate in a failure state:
Otherwise, set node to the previous
entry in the stack of open elements and return to step
2. (This will never fail, since the loop will always terminate in
the previous step if the top of the stack — an
html element — is reached.)
The stack of open elements is said to have an element in table scope when the following algorithm terminates in a match state:
Initialize node to be the current node (the bottommost node of the stack).
If node is the target node, terminate in a match state.
Otherwise, if node is one of the following elements, terminate in a failure state:
Otherwise, set node to the previous
entry in the stack of open elements and return to step
2. (This will never fail, since the loop will always terminate in
the previous step if the top of the stack — an
html element — is reached.)
Nothing happens if at any time any of the elements in the
stack of open elements are moved to a new location in,
or removed from, the Document tree. In particular, the
stack is not changed in this situation. This can cause, amongst
other strange effects, content to be appended to nodes that are no
longer in the DOM.
In some cases (namely, when closing misnested formatting elements), the stack is manipulated in a random-access fashion.
Initially, the list of active formatting elements is empty. It is used to handle mis-nested formatting element tags.
The list contains elements in the formatting
category, and scope markers. The scope markers are inserted when
entering applet elements, buttons, object
elements, marquees, table cells, and table captions, and are used to
prevent formatting from "leaking" into applet elements,
buttons, object elements, marquees, and tables.
In addition, each element in the list of active formatting elements is associated with the token for which it was created, so that further elements can be created for that token if necessary.
When the steps below require the UA to reconstruct the active formatting elements, the UA must perform the following steps:
This has the effect of reopening all the formatting elements that were opened in the current body, cell, or caption (whichever is youngest) that haven't been explicitly closed.
The way this specification is written, the list of active formatting elements always consists of elements in chronological order with the least recently added element first and the most recently added element last (except for while steps 8 to 11 of the above algorithm are being executed, of course).
When the steps below require the UA to clear the list of active formatting elements up to the last marker, the UA must perform the following steps:
Initially, the head element
pointer and the form element
pointer are both null.
Once a head element has been parsed (whether
implicitly or explicitly) the head
element pointer gets set to point to this node.
The form element pointer
points to the last form element that was opened and
whose end tag has not yet been seen. It is used to make form
controls associate with forms in the face of dramatically bad
markup, for historical reasons.
The scripting flag is set to "enabled" if scripting was enabled for the
Document with which the parser is associated when the
parser was created, and "disabled" otherwise.
The frameset-ok flag is set to "ok" when the parser is created. It is set to "not ok" after certain tokens are seen.
Implementations must act as if they used the following state machine to tokenize HTML. The state machine must start in the data state. Most states consume a single character, which may have various side-effects, and either switches the state machine to a new state to reconsume the same character, or switches it to a new state (to consume the next character), or repeats the same state (to consume the next character). Some states have more complicated behavior and can consume several characters before switching to another state.
The exact behavior of certain states depends on a content model flag that is set after certain tokens are emitted. The flag has several states: PCDATA, RCDATA, CDATA, and PLAINTEXT. Initially, it must be in the PCDATA state. In the RCDATA and CDATA states, a further escape flag is used to control the behavior of the tokenizer. It is either true or false, and initially must be set to the false state. The insertion mode and the stack of open elements also affects tokenization.
The output of the tokenization step is a series of zero or more of the following tokens: DOCTYPE, start tag, end tag, comment, character, end-of-file. DOCTYPE tokens have a name, a public identifier, a system identifier, and a force-quirks flag. When a DOCTYPE token is created, its name, public identifier, and system identifier must be marked as missing (which is a distinct state from the empty string), and the force-quirks flag must be set to off (its other state is on). Start and end tag tokens have a tag name, a self-closing flag, and a list of attributes, each of which has a name and a value. When a start or end tag token is created, its self-closing flag must be unset (its other state is that it be set), and its attributes list must be empty. Comment and character tokens have data.
When a token is emitted, it must immediately be handled by the
tree construction stage. The tree construction stage
can affect the state of the content model flag, and can
insert additional characters into the stream. (For example, the
script element can result in scripts executing and
using the dynamic markup insertion APIs to insert
characters into the stream being tokenized.)
When a start tag token is emitted with its self-closing flag set, if the flag is not acknowledged when it is processed by the tree construction stage, that is a parse error.
When an end tag token is emitted, the content model flag must be switched to the PCDATA state.
When an end tag token is emitted with attributes, that is a parse error.
When an end tag token is emitted with its self-closing flag set, that is a parse error.
Before each step of the tokenizer, the user agent must first check the parser pause flag. If it is true, then the tokenizer must abort the processing of any nested invocations of the tokenizer, yielding control back to the caller. If it is false, then the user agent may then check to see if either one of the scripts in the list of scripts that will execute as soon as possible or the first script in the list of scripts that will execute asynchronously, has completed loading. If one has, then it must be executed and removed from its list.
The tokenizer state machine consists of the states defined in the following subsections.
Consume the next input character:
If the content model flag is set to either the RCDATA state or the CDATA state, and the escape flag is false, and there are at least three characters before this one in the input stream, and the last four characters in the input stream, including this one, are U+003C LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+002D HYPHEN-MINUS, and U+002D HYPHEN-MINUS ("<!--"), then set the escape flag to true.
In any case, emit the input character as a character token. Stay in the data state.
If the content model flag is set to either the RCDATA state or the CDATA state, and the escape flag is true, and the last three characters in the input stream including this one are U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS, U+003E GREATER-THAN SIGN ("-->"), set the escape flag to false.
In any case, emit the input character as a character token. Stay in the data state.
(This cannot happen if the content model flag is set to the CDATA state.)
Attempt to consume a character reference, with no additional allowed character.
If nothing is returned, emit a U+0026 AMPERSAND character token.
Otherwise, emit the character token that was returned.
Finally, switch to the data state.
The behavior of this state depends on the content model flag.
Consume the next input character. If it is a U+002F SOLIDUS (/) character, switch to the close tag open state. Otherwise, emit a U+003C LESS-THAN SIGN character token and reconsume the current input character in the data state.
Consume the next input character:
If the content model flag is set to the RCDATA or CDATA states but no start tag token has ever been emitted by this instance of the tokenizer (fragment case), or, if the content model flag is set to the RCDATA or CDATA states and the next few characters do not match the tag name of the last start tag token emitted (compared in an ASCII case-insensitive manner), or if they do but they are not immediately followed by one of the following characters:
...then emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS character token, and switch to the data state to process the next input character.
Otherwise, if the content model flag is set to the PCDATA state, or if the next few characters do match that tag name, consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
When the user agent leaves the attribute name state (and before emitting the tag token, if appropriate), the complete attribute's name must be compared to the other attributes on the same token; if there is already an attribute on the token with the exact same name, then this is a parse error and the new attribute must be dropped, along with the value that gets associated with it (if any).
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Attempt to consume a character reference.
If nothing is returned, append a U+0026 AMPERSAND character to the current attribute's value.
Otherwise, append the returned character token to the current attribute's value.
Finally, switch back to the attribute value state that you were in when were switched into this state.
Consume the next input character:
Consume the next input character:
(This can only happen if the content model flag is set to the PCDATA state.)
Consume every character up to and including the first U+003E GREATER-THAN SIGN character (>) or the end of the file (EOF), whichever comes first. Emit a comment token whose data is the concatenation of all the characters starting from and including the character that caused the state machine to switch into the bogus comment state, up to and including the character immediately before the last consumed character (i.e. up to the character just before the U+003E or EOF character). (If the comment was started by the end of the file (EOF), the token is empty.)
Switch to the data state.
If the end of the file was reached, reconsume the EOF character.
(This can only happen if the content model flag is set to the PCDATA state.)
If the next two characters are both U+002D HYPHEN-MINUS (-) characters, consume those two characters, create a comment token whose data is the empty string, and switch to the comment start state.
Otherwise, if the next seven characters are an ASCII case-insensitive match for the word "DOCTYPE", then consume those characters and switch to the DOCTYPE state.
Otherwise, if the insertion mode is "in foreign content" and the current node is not an element in the HTML namespace and the next seven characters are an ASCII case-sensitive match for the string "[CDATA[" (the five uppercase letters "CDATA" with a U+005B LEFT SQUARE BRACKET character before and after), then consume those characters and switch to the CDATA section state (which is unrelated to the content model flag's CDATA state).
Otherwise, this is a parse error. Switch to the bogus comment state. The next character that is consumed, if any, is the first character that will be in the comment.
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
If the six characters starting from the current input character are an ASCII case-insensitive match for the word "PUBLIC", then consume those characters and switch to the before DOCTYPE public identifier state.
Otherwise, if the six characters starting from the current input character are an ASCII case-insensitive match for the word "SYSTEM", then consume those characters and switch to the before DOCTYPE system identifier state.
Otherwise, this is the parse error. Set the DOCTYPE token's force-quirks flag to on. Switch to the bogus DOCTYPE state.
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
(This can only happen if the content model flag is set to the PCDATA state, and is unrelated to the content model flag's CDATA state.)
Consume every character up to the next occurrence of the three
character sequence U+005D RIGHT SQUARE BRACKET U+005D RIGHT SQUARE
BRACKET U+003E GREATER-THAN SIGN (]]>), or the
end of the file (EOF), whichever comes first. Emit a series of
character tokens consisting of all the characters consumed except
the matching three character sequence at the end (if one was found
before the end of the file).
Switch to the data state.
If the end of the file was reached, reconsume the EOF character.
This section defines how to consume a character reference. This definition is used when parsing character references in text and in attributes.
The behavior depends on the identity of the next character (the one immediately after the U+0026 AMPERSAND character):
Consume the U+0023 NUMBER SIGN.
The behavior further depends on the character after the U+0023 NUMBER SIGN:
Consume the X.
Follow the steps below, but using the range of characters U+0030 DIGIT ZERO through to U+0039 DIGIT NINE, U+0061 LATIN SMALL LETTER A through to U+0066 LATIN SMALL LETTER F, and U+0041 LATIN CAPITAL LETTER A, through to U+0046 LATIN CAPITAL LETTER F (in other words, 0-9, A-F, a-f).
When it comes to interpreting the number, interpret it as a hexadecimal number.
Follow the steps below, but using the range of characters U+0030 DIGIT ZERO through to U+0039 DIGIT NINE (i.e. just 0-9).
When it comes to interpreting the number, interpret it as a decimal number.
Consume as many characters as match the range of characters given above.
If no characters match the range, then don't consume any characters (and unconsume the U+0023 NUMBER SIGN character and, if appropriate, the X character). This is a parse error; nothing is returned.
Otherwise, if the next character is a U+003B SEMICOLON, consume that too. If it isn't, there is a parse error.
If one or more characters match the range, then take them all and interpret the string of characters as a number (either hexadecimal or decimal as appropriate).
If that number is one of the numbers in the first column of the following table, then this is a parse error. Find the row with that number in the first column, and return a character token for the Unicode character given in the second column of that row.
| Number | Unicode character | |
|---|---|---|
| 0x0D | U+000A | LINE FEED (LF) |
| 0x80 | U+20AC | EURO SIGN ('€') |
| 0x81 | U+FFFD | REPLACEMENT CHARACTER |
| 0x82 | U+201A | SINGLE LOW-9 QUOTATION MARK ('‚') |
| 0x83 | U+0192 | LATIN SMALL LETTER F WITH HOOK ('ƒ') |
| 0x84 | U+201E | DOUBLE LOW-9 QUOTATION MARK ('„') |
| 0x85 | U+2026 | HORIZONTAL ELLIPSIS ('…') |
| 0x86 | U+2020 | DAGGER ('†') |
| 0x87 | U+2021 | DOUBLE DAGGER ('‡') |
| 0x88 | U+02C6 | MODIFIER LETTER CIRCUMFLEX ACCENT ('ˆ') |
| 0x89 | U+2030 | PER MILLE SIGN ('‰') |
| 0x8A | U+0160 | LATIN CAPITAL LETTER S WITH CARON ('Š') |
| 0x8B | U+2039 | SINGLE LEFT-POINTING ANGLE QUOTATION MARK ('‹') |
| 0x8C | U+0152 | LATIN CAPITAL LIGATURE OE ('Œ') |
| 0x8D | U+FFFD | REPLACEMENT CHARACTER |
| 0x8E | U+017D | LATIN CAPITAL LETTER Z WITH CARON ('Ž') |
| 0x8F | U+FFFD | REPLACEMENT CHARACTER |
| 0x90 | U+FFFD | REPLACEMENT CHARACTER |
| 0x91 | U+2018 | LEFT SINGLE QUOTATION MARK ('‘') |
| 0x92 | U+2019 | RIGHT SINGLE QUOTATION MARK ('’') |
| 0x93 | U+201C | LEFT DOUBLE QUOTATION MARK ('“') |
| 0x94 | U+201D | RIGHT DOUBLE QUOTATION MARK ('”') |
| 0x95 | U+2022 | BULLET ('•') |
| 0x96 | U+2013 | EN DASH ('–') |
| 0x97 | U+2014 | EM DASH ('—') |
| 0x98 | U+02DC | SMALL TILDE ('˜') |
| 0x99 | U+2122 | TRADE MARK SIGN ('™') |
| 0x9A | U+0161 | LATIN SMALL LETTER S WITH CARON ('š') |
| 0x9B | U+203A | SINGLE RIGHT-POINTING ANGLE QUOTATION MARK ('›') |
| 0x9C | U+0153 | LATIN SMALL LIGATURE OE ('œ') |
| 0x9D | U+FFFD | REPLACEMENT CHARACTER |
| 0x9E | U+017E | LATIN SMALL LETTER Z WITH CARON ('ž') |
| 0x9F | U+0178 | LATIN CAPITAL LETTER Y WITH DIAERESIS ('Ÿ') |
Otherwise, if the number is in the range 0x0000 to 0x0008, 0x000E to 0x001F, 0x007F to 0x009F, 0xD800 to 0xDFFF, 0xFDD0 to 0xFDEF, or is one of 0x000B, 0xFFFE, 0xFFFF, 0x1FFFE, 0x1FFFF, 0x2FFFE, 0x2FFFF, 0x3FFFE, 0x3FFFF, 0x4FFFE, 0x4FFFF, 0x5FFFE, 0x5FFFF, 0x6FFFE, 0x6FFFF, 0x7FFFE, 0x7FFFF, 0x8FFFE, 0x8FFFF, 0x9FFFE, 0x9FFFF, 0xAFFFE, 0xAFFFF, 0xBFFFE, 0xBFFFF, 0xCFFFE, 0xCFFFF, 0xDFFFE, 0xDFFFF, 0xEFFFE, 0xEFFFF, 0xFFFFE, 0xFFFFF, 0x10FFFE, or 0x10FFFF, or is higher than 0x10FFFF, then this is a parse error; return a character token for the U+FFFD REPLACEMENT CHARACTER character instead.
Otherwise, return a character token for the Unicode character whose code point is that number.
Consume the maximum number of characters possible, with the consumed characters matching one of the identifiers in the first column of the named character references table (in a case-sensitive manner).
If no match can be made, then this is a parse error. No characters are consumed, and nothing is returned.
If the last character matched is not a U+003B SEMICOLON (;), there is a parse error.
If the character reference is being consumed as part of an
attribute, and the last character matched is not a U+003B
SEMICOLON (;), and the next character is in
the range U+0030 DIGIT ZERO to U+0039 DIGIT NINE, U+0041 LATIN
CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z, or U+0061 LATIN
SMALL LETTER A to U+007A LATIN SMALL LETTER Z, then, for
historical reasons, all the characters that were matched after the
U+0026 AMPERSAND (&) must be unconsumed, and nothing is
returned.
Otherwise, return a character token for the character corresponding to the character reference name (as given by the second column of the named character references table).
If the markup contains I'm ¬it; I tell
you, the character reference is parsed as "not", as in,
I'm ¬it; I tell you. But if the markup
was I'm ∉ I tell you, the
character reference would be parsed as "notin;", resulting in
I'm ∉ I tell you.
The input to the tree construction stage is a sequence of tokens
from the tokenization stage. The tree construction
stage is associated with a DOM Document object when a
parser is created. The "output" of this stage consists of
dynamically modifying or extending that document's DOM tree.
This specification does not define when an interactive user agent
has to render the Document so that it is available to
the user, or when it has to begin accepting user input.
As each token is emitted from the tokenizer, the user agent must process the token according to the rules given in the section corresponding to the current insertion mode.
When the steps below require the UA to insert a
character into a node, if that node has a child immediately
before where the character is to be inserted, and that child is a
Text node, and that Text node was the last
node that the parser inserted into the document, then the character
must be appended to that Text node; otherwise, a new
Text node whose data is just that character must be
inserted in the appropriate place.
DOM mutation events must not fire
for changes caused by the UA parsing the document. (Conceptually,
the parser is not mutating the DOM, it is constructing it.) This
includes the parsing of any content inserted using document.write() and document.writeln() calls. [DOM3EVENTS]
Not all of the tag names mentioned below are conformant tag names in this specification; many are included to handle legacy content. They still form part of the algorithm that implementations are required to implement to claim conformance.
The algorithm described below places no limit on the depth of the DOM tree generated, or on the length of tag names, attribute names, attribute values, text nodes, etc. While implementors are encouraged to avoid arbitrary limits, it is recognized that practical concerns will likely force user agents to impose nesting depths.
When the steps below require the UA to create an element for a token in a
particular namespace, the UA must create a node implementing the
interface appropriate for the element type corresponding to the tag
name of the token in the given namespace (as given in the
specification that defines that element, e.g. for an a
element in the HTML namespace, this specification
defines it to be the HTMLAnchorElement interface), with
the tag name being the name of that element, with the node being in
the given namespace, and with the attributes on the node being those
given in the given token.
The interface appropriate for an element in the HTML
namespace that is not defined in this specification is
HTMLElement. The interface appropriate for an element
in another namespace that is not defined by that namespace's
specification is Element.
When a resettable element is created in this manner, its reset algorithm must be invoked once the attributes are set. (This initializes the element's value and checkedness based on the element's attributes.)
When the steps below require the UA to insert an HTML element for a token, the UA must first create an element for the token in the HTML namespace, and then append this node to the current node, and push it onto the stack of open elements so that it is the new current node.
The steps below may also require that the UA insert an HTML element in a particular place, in which case the UA must follow the same steps except that it must insert or append the new node in the location specified instead of appending it to the current node. (This happens in particular during the parsing of tables with invalid content.)
If an element created by the insert an HTML element
algorithm is a form-associated element, and the
form element pointer is not null,
and the newly created element doesn't have a form attribute, the user agent must
associate the newly
created element with the form element pointed to by the
form element pointer before
inserting it wherever it is to be inserted.
When the steps below require the UA to insert a foreign
element for a token, the UA must first create an element
for the token in the given namespace, and then append this
node to the current node, and push it onto the
stack of open elements so that it is the new
current node. If the newly created element has an xmlns attribute in the XMLNS namespace
whose value is not exactly the same as the element's namespace, that
is a parse error. Similarly, if the newly created
element has an xmlns:xlink attribute in the
XMLNS namespace whose value is not the XLink
Namespace, that is a parse error.
When the steps below require the user agent to adjust MathML
attributes for a token, then, if the token has an attribute
named definitionurl, change its name to definitionURL (note the case difference).
When the steps below require the user agent to adjust SVG attributes for a token, then, for each attribute on the token whose attribute name is one of the ones in the first column of the following table, change the attribute's name to the name given in the corresponding cell in the second column. (This fixes the case of SVG attributes that are not all lowercase.)
| Attribute name on token | Attribute name on element |
|---|---|
attributename | attributeName
|
attributetype | attributeType
|
basefrequency | baseFrequency
|
baseprofile | baseProfile
|
calcmode | calcMode
|
clippathunits | clipPathUnits
|
contentscripttype | contentScriptType
|
contentstyletype | contentStyleType
|
diffuseconstant | diffuseConstant
|
edgemode | edgeMode
|
externalresourcesrequired | externalResourcesRequired
|
filterres | filterRes
|
filterunits | filterUnits
|
glyphref | glyphRef
|
gradienttransform | gradientTransform
|
gradientunits | gradientUnits
|
kernelmatrix | kernelMatrix
|
kernelunitlength | kernelUnitLength
|
keypoints | keyPoints
|
keysplines | keySplines
|
keytimes | keyTimes
|
lengthadjust | lengthAdjust
|
limitingconeangle | limitingConeAngle
|
markerheight | markerHeight
|
markerunits | markerUnits
|
markerwidth | markerWidth
|
maskcontentunits | maskContentUnits
|
maskunits | maskUnits
|
numoctaves | numOctaves
|
pathlength | pathLength
|
patterncontentunits | patternContentUnits
|
patterntransform | patternTransform
|
patternunits | patternUnits
|
pointsatx | pointsAtX
|
pointsaty | pointsAtY
|
pointsatz | pointsAtZ
|
preservealpha | preserveAlpha
|
preserveaspectratio | preserveAspectRatio
|
primitiveunits | primitiveUnits
|
refx | refX
|
refy | refY
|
repeatcount | repeatCount
|
repeatdur | repeatDur
|
requiredextensions | requiredExtensions
|
requiredfeatures | requiredFeatures
|
specularconstant | specularConstant
|
specularexponent | specularExponent
|
spreadmethod | spreadMethod
|
startoffset | startOffset
|
stddeviation | stdDeviation
|
stitchtiles | stitchTiles
|
surfacescale | surfaceScale
|
systemlanguage | systemLanguage
|
tablevalues | tableValues
|
targetx | targetX
|
targety | targetY
|
textlength | textLength
|
viewbox | viewBox
|
viewtarget | viewTarget
|
xchannelselector | xChannelSelector
|
ychannelselector | yChannelSelector
|
zoomandpan | zoomAndPan
|
When the steps below require the user agent to adjust
foreign attributes for a token, then, if any of the attributes
on the token match the strings given in the first column of the
following table, let the attribute be a namespaced attribute, with
the prefix being the string given in the corresponding cell in the
second column, the local name being the string given in the
corresponding cell in the third column, and the namespace being the
namespace given in the corresponding cell in the fourth
column. (This fixes the use of namespaced attributes, in particular
xml:lang.)
| Attribute name | Prefix | Local name | Namespace |
|---|---|---|---|
xlink:actuate | xlink | actuate | XLink namespace |
xlink:arcrole | xlink | arcrole | XLink namespace |
xlink:href | xlink | href | XLink namespace |
xlink:role | xlink | role | XLink namespace |
xlink:show | xlink | show | XLink namespace |
xlink:title | xlink | title | XLink namespace |
xlink:type | xlink | type | XLink namespace |
xml:base | xml | base | XML namespace |
xml:lang | xml | lang | XML namespace |
xml:space | xml | space | XML namespace |
xmlns | (none) | xmlns | XMLNS namespace |
xmlns:xlink | xmlns | xlink | XMLNS namespace |
The generic CDATA element parsing algorithm and the generic RCDATA element parsing algorithm consist of the following steps. These algorithms are always invoked in response to a start tag token.
Insert an HTML element for the token.
If the algorithm that was invoked is the generic CDATA element parsing algorithm, switch the tokenizer's content model flag to the CDATA state; otherwise the algorithm invoked was the generic RCDATA element parsing algorithm, switch the tokenizer's content model flag to the RCDATA state.
Let the original insertion mode be the current insertion mode.
Then, switch the insertion mode to "in CDATA/RCDATA".
When the steps below require the UA to generate implied end
tags, then, while the current node is a
dd element, a dt element, an
li element, an option element, an
optgroup element, a p element, an
rp element, or an rt element, the UA must
pop the current node off the stack of open
elements.
If a step requires the UA to generate implied end tags but lists an element to exclude from the process, then the UA must perform the above steps as if that element was not in the above list.
Foster parenting happens when content is misnested in tables.
When a node node is to be foster parented, the node node must be inserted into the foster parent element, and the current table must be marked as tainted. (Once the current table has been tainted, whitespace characters are inserted into the foster parent element instead of the current node.)
The foster parent element is the parent element of the
last table element in the stack of open
elements, if there is a table element and it has
such a parent element. If there is no table element in
the stack of open elements (fragment
case), then the foster parent element is the first
element in the stack of open elements (the
html element). Otherwise, if there is a
table element in the stack of open
elements, but the last table element in the
stack of open elements has no parent, or its parent
node is not an element, then the foster parent element is
the element before the last table element in the
stack of open elements.
If the foster parent element is the parent element of the
last table element in the stack of open
elements, then node must be inserted
immediately before the last table element in
the stack of open elements in the foster parent
element; otherwise, node must be
appended to the foster parent element.
When the insertion mode is "initial", tokens must be handled as follows:
Ignore the token.
Append a Comment node to the Document
object with the data attribute set to the
data given in the comment token.
If the DOCTYPE token's name is not a
case-sensitive match for the string "html", or if the token's public identifier is not
missing, or if the token's system identifier is neither missing
nor a case-sensitive match for the string
"about:legacy-compat", then there is a parse
error (this is the DOCTYPE parse
error). Conformance checkers may, instead of reporting this
error, switch to a conformance checking mode for another language
(e.g. based on the DOCTYPE token a conformance checker could
recognize that the document is an HTML4-era document, and defer to
an HTML4 conformance checker.)
Append a DocumentType node to the
Document node, with the name
attribute set to the name given in the DOCTYPE token, or the empty
string if the name was missing; the publicId
attribute set to the public identifier given in the DOCTYPE token,
or the empty string if the public identifier was missing; the
systemId attribute set to the system
identifier given in the DOCTYPE token, or the empty string if the
system identifier was missing; and the other attributes specific
to DocumentType objects set to null and empty lists
as appropriate. Associate the DocumentType node with
the Document object so that it is returned as the
value of the doctype attribute of the
Document object.
Then, if the DOCTYPE token matches one of the conditions in the following list, then set the document to quirks mode:
HTML". +//Silmaril//dtd html Pro v0r11 19970101//" -//AdvaSoft Ltd//DTD HTML 3.0 asWedit + extensions//" -//AS//DTD HTML 3.0 asWedit + extensions//" -//IETF//DTD HTML 2.0 Level 1//" -//IETF//DTD HTML 2.0 Level 2//" -//IETF//DTD HTML 2.0 Strict Level 1//" -//IETF//DTD HTML 2.0 Strict Level 2//" -//IETF//DTD HTML 2.0 Strict//" -//IETF//DTD HTML 2.0//" -//IETF//DTD HTML 2.1E//" -//IETF//DTD HTML 3.0//" -//IETF//DTD HTML 3.2 Final//" -//IETF//DTD HTML 3.2//" -//IETF//DTD HTML 3//" -//IETF//DTD HTML Level 0//" -//IETF//DTD HTML Level 1//" -//IETF//DTD HTML Level 2//" -//IETF//DTD HTML Level 3//" -//IETF//DTD HTML Strict Level 0//" -//IETF//DTD HTML Strict Level 1//" -//IETF//DTD HTML Strict Level 2//" -//IETF//DTD HTML Strict Level 3//" -//IETF//DTD HTML Strict//" -//IETF//DTD HTML//" -//Metrius//DTD Metrius Presentational//" -//Microsoft//DTD Internet Explorer 2.0 HTML Strict//" -//Microsoft//DTD Internet Explorer 2.0 HTML//" -//Microsoft//DTD Internet Explorer 2.0 Tables//" -//Microsoft//DTD Internet Explorer 3.0 HTML Strict//" -//Microsoft//DTD Internet Explorer 3.0 HTML//" -//Microsoft//DTD Internet Explorer 3.0 Tables//" -//Netscape Comm. Corp.//DTD HTML//" -//Netscape Comm. Corp.//DTD Strict HTML//" -//O'Reilly and Associates//DTD HTML 2.0//" -//O'Reilly and Associates//DTD HTML Extended 1.0//" -//O'Reilly and Associates//DTD HTML Extended Relaxed 1.0//" -//SoftQuad Software//DTD HoTMetaL PRO 6.0::19990601::extensions to HTML 4.0//" -//SoftQuad//DTD HoTMetaL PRO 4.0::19971010::extensions to HTML 4.0//" -//Spyglass//DTD HTML 2.0 Extended//" -//SQ//DTD HTML 2.0 HoTMetaL + extensions//" -//Sun Microsystems Corp.//DTD HotJava HTML//" -//Sun Microsystems Corp.//DTD HotJava Strict HTML//" -//W3C//DTD HTML 3 1995-03-24//" -//W3C//DTD HTML 3.2 Draft//" -//W3C//DTD HTML 3.2 Final//" -//W3C//DTD HTML 3.2//" -//W3C//DTD HTML 3.2S Draft//" -//W3C//DTD HTML 4.0 Frameset//" -//W3C//DTD HTML 4.0 Transitional//" -//W3C//DTD HTML Experimental 19960712//" -//W3C//DTD HTML Experimental 970421//" -//W3C//DTD W3 HTML//" -//W3O//DTD W3 HTML 3.0//" -//W3O//DTD W3 HTML Strict 3.0//EN//" -//WebTechs//DTD Mozilla HTML 2.0//" -//WebTechs//DTD Mozilla HTML//" -/W3C/DTD HTML 4.0 Transitional/EN" HTML" http://www.ibm.com/data/dtd/v11/ibmxhtml1-transitional.dtd" -//W3C//DTD HTML 4.01 Frameset//" -//W3C//DTD HTML 4.01 Transitional//" Otherwise, if the DOCTYPE token matches one of the conditions in the following list, then set the document to limited quirks mode:
-//W3C//DTD XHTML 1.0 Frameset//" -//W3C//DTD XHTML 1.0 Transitional//" -//W3C//DTD HTML 4.01 Frameset//" -//W3C//DTD HTML 4.01 Transitional//" The name, system identifier, and public identifier strings must be compared to the values given in the lists above in an ASCII case-insensitive manner. A system identifier whose value is the empty string is not considered missing for the purposes of the conditions above.
Then, switch the insertion mode to "before html".
Set the document to quirks mode.
Switch the insertion mode to "before html", then reprocess the current token.
When the insertion mode is "before html", tokens must be handled as follows:
Parse error. Ignore the token.
Append a Comment node to the Document
object with the data attribute set to the
data given in the comment token.
Ignore the token.
Create an element for the token in the HTML
namespace. Append it to the Document
object. Put this element in the stack of open
elements.
If the Document is being
loaded as part of navigation of a
browsing context, then: if the newly created element
has a manifest attribute,
then resolve the value of that
attribute to an absolute URL, relative to the newly
created element, and if that is successful, run the application cache selection
algorithm with the resulting absolute URL;
otherwise, if there is no such attribute or resolving it fails,
run the application cache
selection algorithm with no manifest. The algorithm must be
passed the Document object.
Switch the insertion mode to "before head".
Create an html element. Append it to the
Document object. Put this element in the stack
of open elements.
If the Document is being loaded as part of navigation of a browsing
context, then: run the application cache selection
algorithm with no manifest, passing it the
Document object.
Switch the insertion mode to "before head", then reprocess the current token.
Should probably make end tags be ignored, so that "</head><!-- --><html>" puts the comment before the root node (or should we?)
The root element can end up being removed from the
Document object, e.g. by scripts; nothing in particular
happens in such cases, content continues being appended to the nodes
as described in the next section.
When the insertion mode is "before head", tokens must be handled as follows:
Ignore the token.
Append a Comment node to the current
node with the data attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Insert an HTML element for the token.
Set the head element pointer
to the newly created head element.
Switch the insertion mode to "in head".
Act as if a start tag token with the tag name "head" and no attributes had been seen, then reprocess the current token.
Parse error. Ignore the token.
Act as if a start tag token with the tag name "head" and no attributes had been seen, then reprocess the current token.
This will result in an empty head
element being generated, with the current token being
reprocessed in the "after head" insertion mode.
When the insertion mode is "in head", tokens must be handled as follows:
Insert the character into the current node.
Append a Comment node to the current
node with the data attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
If the element has a charset attribute, and its
value is a supported encoding, and the confidence is
currently tentative, then change the
encoding to the encoding given by the value of the
charset attribute.
Otherwise, if the element has a content attribute, and
applying the algorithm for extracting an encoding from a
Content-Type to its value returns a supported encoding
encoding, and the confidence is
currently tentative, then change the
encoding to the encoding encoding.
Follow the generic RCDATA element parsing algorithm.
Follow the generic CDATA element parsing algorithm.
Insert an HTML element for the token.
Switch the insertion mode to "in head noscript".
Mark the element as being "parser-inserted".
This ensures that, if the script is external,
any document.write()
calls in the script will execute in-line, instead of blowing the
document away, as would happen in most other cases. It also
prevents the script from executing until the end tag is
seen.
If the parser was originally created for the HTML
fragment parsing algorithm, then mark the
script element as "already
executed". (fragment case)
Append the new element to the current node and push it onto the stack of open elements.
Switch the tokenizer's content model flag to the CDATA state.
Let the original insertion mode be the current insertion mode.
Switch the insertion mode to "in CDATA/RCDATA".
Pop the current node (which will be the
head element) off the stack of open
elements.
Switch the insertion mode to "after head".
Act as described in the "anything else" entry below.
Parse error. Ignore the token.
Act as if an end tag token with the tag name "head" had been seen, and reprocess the current token.
In certain UAs, some elements don't trigger the "in body" mode straight away, but instead get put into the head. Do we want to copy that?
When the insertion mode is "in head noscript", tokens must be handled as follows:
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Pop the current node (which will be a
noscript element) from the stack of open
elements; the new current node will be a
head element.
Switch the insertion mode to "in head".
Process the token using the rules for the "in head" insertion mode.
Act as described in the "anything else" entry below.
Parse error. Ignore the token.
Parse error. Act as if an end tag with the tag name "noscript" had been seen and reprocess the current token.
When the insertion mode is "after head", tokens must be handled as follows:
Insert the character into the current node.
Append a Comment node to the current
node with the data attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Insert an HTML element for the token.
Switch the insertion mode to "in body".
Insert an HTML element for the token.
Switch the insertion mode to "in frameset".
Push the node pointed to by the head element pointer onto the
stack of open elements.
Process the token using the rules for the "in head" insertion mode.
Remove the node pointed to by the head element pointer from the stack
of open elements.
The head element
pointer cannot be null at this point.
Act as described in the "anything else" entry below.
Parse error. Ignore the token.
Act as if a start tag token with the tag name "body" and no attributes had been seen, and then reprocess the current token.
When the insertion mode is "in body", tokens must be handled as follows:
Reconstruct the active formatting elements, if any.
Insert the token's character into the current node.
If the token is not one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), or U+0020 SPACE, then set the frameset-ok flag to "not ok".
Append a Comment node to the current
node with the data attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Parse error. For each attribute on the token, check to see if the attribute is already present on the top element of the stack of open elements. If it is not, add the attribute and its corresponding value to that element.
Process the token using the rules for the "in head" insertion mode.
If the second element on the stack of open
elements is not a body element, or, if the
stack of open elements has only one node on it,
then ignore the token. (fragment case)
Otherwise, for each attribute on the token, check to see if
the attribute is already present on the body
element (the second element) on the stack of open
elements. If it is not, add the attribute and its
corresponding value to that element.
If the second element on the stack of open
elements is not a body element, or, if the
stack of open elements has only one node on it,
then ignore the token. (fragment case)
If the frameset-ok flag is set to "not ok", ignore the token.
Otherwise, run the following steps:
Remove the second element on the stack of open elements from its parent node, if it has one.
Pop all the nodes from the bottom of the stack of
open elements, from the current node up to
the root html element.
Insert an HTML element for the token.
Switch the insertion mode to "in frameset".
If there is a node in the stack of open elements
that is not either a dd element, a dt
element, an li element, a p element, a
tbody element, a td element, a
tfoot element, a th element, a
thead element, a tr element, the
body element, or the html element, then
this is a parse error.
If the stack of open elements does not have a body element
in scope, this is a parse error; ignore the
token.
Otherwise, if there is a node in the stack of open
elements that is not either a dd element, a
dt element, an li element, an
optgroup element, an option element, a
p element, an rp element, an
rt element, a tbody element, a
td element, a tfoot element, a
th element, a thead element, a
tr element, the body element, or the
html element, then this is a parse
error.
Switch the insertion mode to "after body".
Act as if an end tag with tag name "body" had been seen, then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the fragment case.
If the stack of open elements has a p element in
scope, then act as if an end tag with the tag name
"p" had been seen.
Insert an HTML element for the token.
If the stack of open elements has a p element in
scope, then act as if an end tag with the tag name
"p" had been seen.
If the current node is an element whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6", then this is a parse error; pop the current node off the stack of open elements.
Insert an HTML element for the token.
If the stack of open elements has a p element in
scope, then act as if an end tag with the tag name
"p" had been seen.
Insert an HTML element for the token.
If the next token is a U+000A LINE FEED (LF) character
token, then ignore that token and move on to the next
one. (Newlines at the start of pre blocks are
ignored as an authoring convenience.)
Set the frameset-ok flag to "not ok".
If the form element
pointer is not null, then this is a parse
error; ignore the token.
Otherwise:
If the stack of open elements has a p element in
scope, then act as if an end tag with the tag name
"p" had been seen.
Insert an HTML element for the token, and set the
form element pointer to
point to the element created.
Run the following algorithm:
Set the frameset-ok flag to "not ok".
Initialize node to be the current node (the bottommost node of the stack).
If node is an li element,
then act as if an end tag with the tag name "li" had
been seen, then jump to the last step.
If node is not in the
formatting category, and is not in the
phrasing category, and is not an
address, div, or p
element, then jump to the last step.
Otherwise, set node to the previous entry in the stack of open elements and return to step 2.
This is the last step.
If the stack of open elements has a p element in
scope, then act as if an end tag with the tag name
"p" had been seen.
Finally, insert an HTML element for the token.
Run the following algorithm:
Set the frameset-ok flag to "not ok".
Initialize node to be the current node (the bottommost node of the stack).
If node is a dd or
dt element, then act as if an end tag with the same
tag name as node had been seen, then jump to
the last step.
If node is not in the
formatting category, and is not in the
phrasing category, and is not an
address, div, or p
element, then jump to the last step.
Otherwise, set node to the previous entry in the stack of open elements and return to step 2.
This is the last step.
If the stack of open elements has a p element in
scope, then act as if an end tag with the tag name
"p" had been seen.
Finally, insert an HTML element for the token.
If the stack of open elements has a p element in
scope, then act as if an end tag with the tag name
"p" had been seen.
Insert an HTML element for the token.
Switch the content model flag to the PLAINTEXT state.
Once a start tag with the tag name "plaintext" has been seen, that will be the last token ever seen other than character tokens (and the end-of-file token), because there is no way to switch the content model flag out of the PLAINTEXT state.
If the stack of open elements does not have an element in scope with the same tag name as that of the token, then this is a parse error; ignore the token.
Otherwise, run these steps:
If the current node is not an element with the same tag name as that of the token, then this is a parse error.
Pop elements from the stack of open elements until an element with the same tag name as the token has been popped from the stack.
Let node be the element that the
form element pointer is set
to.
Set the form element pointer
to null.
If node is null or the stack of open elements does not have node in scope, then this is a parse error; ignore the token.
Otherwise, run these steps:
If the current node is not node, then this is a parse error.
Remove node from the stack of open elements.
If the stack of open elements does not have an element in scope with the same tag name as that of the token, then this is a parse error; act as if a start tag with the tag name "p" had been seen, then reprocess the current token.
Otherwise, run these steps:
Generate implied end tags, except for elements with the same tag name as the token.
If the current node is not an element with the same tag name as that of the token, then this is a parse error.
Pop elements from the stack of open elements until an element with the same tag name as the token has been popped from the stack.
If the stack of open elements does not have an element in scope with the same tag name as that of the token, then this is a parse error; ignore the token.
Otherwise, run these steps:
Generate implied end tags, except for elements with the same tag name as the token.
If the current node is not an element with the same tag name as that of the token, then this is a parse error.
Pop elements from the stack of open elements until an element with the same tag name as the token has been popped from the stack.
If the stack of open elements does not have an element in scope whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6", then this is a parse error; ignore the token.
Otherwise, run these steps:
If the current node is not an element with the same tag name as that of the token, then this is a parse error.
Pop elements from the stack of open elements until an element whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6" has been popped from the stack.
Take a deep breath, then act as described in the "any other end tag" entry below.
If the list of active formatting elements contains an element whose tag name is "a" between the end of the list and the last marker on the list (or the start of the list if there is no marker on the list), then this is a parse error; act as if an end tag with the tag name "a" had been seen, then remove that element from the list of active formatting elements and the stack of open elements if the end tag didn't already remove it (it might not have if the element is not in table scope).
In the non-conforming stream
<a href="a">a<table><a href="b">b</table>x,
the first a element would be closed upon seeing
the second one, and the "x" character would be inside a link
to "b", not to "a". This is despite the fact that the outer
a element is not in table scope (meaning that a
regular </a> end tag at the start of the table
wouldn't close the outer a element).
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Add that element to the list of active formatting elements.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Add that element to the list of active formatting elements.
Reconstruct the active formatting elements, if any.
If the stack of open elements has a nobr element in scope,
then this is a parse error; act as if an end tag with
the tag name "nobr" had been seen, then once again
reconstruct the active formatting elements, if
any.
Insert an HTML element for the token. Add that element to the list of active formatting elements.
Follow these steps:
Let the formatting element be the last element in the list of active formatting elements that:
If there is no such node, or, if that node is also in the stack of open elements but the element is not in scope, then this is a parse error; ignore the token, and abort these steps.
Otherwise, if there is such a node, but that node is not in the stack of open elements, then this is a parse error; remove the element from the list, and abort these steps.
Otherwise, there is a formatting element and that element is in the stack and is in scope. If the element is not the current node, this is a parse error. In any case, proceed with the algorithm as written in the following steps.
Let the furthest block be the topmost node in the stack of open elements that is lower in the stack than the formatting element, and is not an element in the phrasing or formatting categories. There might not be one.
If there is no furthest block, then the UA must skip the subsequent steps and instead just pop all the nodes from the bottom of the stack of open elements, from the current node up to and including the formatting element, and remove the formatting element from the list of active formatting elements.
Let the common ancestor be the element immediately above the formatting element in the stack of open elements.
Let a bookmark note the position of the formatting element in the list of active formatting elements relative to the elements on either side of it in the list.
Let node and last node be the furthest block. Follow these steps:
If the common ancestor node is a
table, tbody, tfoot,
thead, or tr element, then,
foster parent whatever last
node ended up being in the previous step, first removing
it from its previous parent node if any.
Otherwise, append whatever last node ended up being in the previous step to the common ancestor node, first removing it from its previous parent node if any.
Create an element for the token for which the formatting element was created.
Take all of the child nodes of the furthest block and append them to the element created in the last step.
Append that new element to the furthest block.
Remove the formatting element from the list of active formatting elements, and insert the new element into the list of active formatting elements at the position of the aforementioned bookmark.
Remove the formatting element from the stack of open elements, and insert the new element into the stack of open elements immediately below the position of the furthest block in that stack.
Jump back to step 1 in this series of steps.
Because of the way this algorithm causes elements to change parents, it has been dubbed the "adoption agency algorithm" (in contrast with other possibly algorithms for dealing with misnested content, which included the "incest algorithm", the "secret affair algorithm", and the "Heisenberg algorithm").
If the stack of open elements has a button element in
scope, then this is a parse error;
act as if an end tag with the tag name "button" had been seen,
then reprocess the token.
Otherwise:
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
Insert a marker at the end of the list of active formatting elements.
Set the frameset-ok flag to "not ok".
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
Insert a marker at the end of the list of active formatting elements.
Set the frameset-ok flag to "not ok".
If the stack of open elements does not have an element in scope with the same tag name as that of the token, then this is a parse error; ignore the token.
Otherwise, run these steps:
If the current node is not an element with the same tag name as that of the token, then this is a parse error.
Pop elements from the stack of open elements until an element with the same tag name as the token has been popped from the stack.
If the stack of open elements has a p element in
scope, then act as if an end tag with the tag name
"p" had been seen.
Insert an HTML element for the token.
Set the frameset-ok flag to "not ok".
Switch the insertion mode to "in table".
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
Set the frameset-ok flag to "not ok".
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
If the stack of open elements has a p element in
scope, then act as if an end tag with the tag name
"p" had been seen.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
Set the frameset-ok flag to "not ok".
Parse error. Change the token's tag name to "img" and reprocess it. (Don't ask.)
If the form element
pointer is not null, then ignore the token.
Otherwise:
Acknowledge the token's self-closing flag, if it is set.
Act as if a start tag token with the tag name "form" had been seen.
If the token has an attribute called "action", set the
action attribute on the
resulting form element to the value of the
"action" attribute of the token.
Act as if a start tag token with the tag name "hr" had been seen.
Act as if a start tag token with the tag name "p" had been seen.
Act as if a start tag token with the tag name "label" had been seen.
Act as if a stream of character tokens had been seen (see below for what they should say).
Act as if a start tag token with the tag name "input" had been
seen, with all the attributes from the "isindex" token except
"name", "action", and "prompt". Set the name attribute of the resulting
input element to the value "isindex".
Act as if a stream of character tokens had been seen (see below for what they should say).
Act as if an end tag token with the tag name "label" had been seen.
Act as if an end tag token with the tag name "p" had been seen.
Act as if a start tag token with the tag name "hr" had been seen.
Act as if an end tag token with the tag name "form" had been seen.
If the token has an attribute with the name "prompt", then the
first stream of characters must be the same string as given in
that attribute, and the second stream of characters must be
empty. Otherwise, the two streams of character tokens together
should, together with the input element, express the
equivalent of "This is a searchable index. Insert your search
keywords here: (input field)" in the user's preferred
language.
Insert an HTML element for the token.
If the next token is a U+000A LINE FEED (LF) character
token, then ignore that token and move on to the next
one. (Newlines at the start of textarea elements are
ignored as an authoring convenience.)
Switch the tokenizer's content model flag to the RCDATA state.
Let the original insertion mode be the current insertion mode.
Set the frameset-ok flag to "not ok".
Switch the insertion mode to "in CDATA/RCDATA".
Reconstruct the active formatting elements, if any.
Set the frameset-ok flag to "not ok".
Follow the generic CDATA element parsing algorithm.
Set the frameset-ok flag to "not ok".
Follow the generic CDATA element parsing algorithm.
Follow the generic CDATA element parsing algorithm.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
Set the frameset-ok flag to "not ok".
If the insertion mode is one of in table", "in caption", "in column group", "in table body", "in row", or "in cell", then switch the insertion mode to "in select in table". Otherwise, switch the insertion mode to "in select".
If the stack of open elements has an option element in
scope, then act as if an end tag with the tag name "option"
had been seen.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
If the stack of open elements has a ruby element in scope,
then generate implied end tags. If the current
node is not then a ruby element, this is a
parse error; pop all the nodes from the current
node up to the node immediately before the bottommost
ruby element on the stack of open
elements.
Insert an HTML element for the token.
Parse error. Act as if a start tag token with the tag name "br" had been seen. Ignore the end tag token.
Reconstruct the active formatting elements, if any.
Adjust MathML attributes for the token. (This fixes the case of MathML attributes that are not all lowercase.)
Adjust foreign attributes for the token. (This fixes the use of namespaced attributes, in particular XLink.)
Insert a foreign element for the token, in the MathML namespace.
If the token has its self-closing flag set, pop the current node off the stack of open elements and acknowledge the token's self-closing flag.
Otherwise, if the insertion mode is not already "in foreign content", let the secondary insertion mode be the current insertion mode, and then switch the insertion mode to "in foreign content".
Reconstruct the active formatting elements, if any.
Adjust SVG attributes for the token. (This fixes the case of SVG attributes that are not all lowercase.)
Adjust foreign attributes for the token. (This fixes the use of namespaced attributes, in particular XLink in SVG.)
Insert a foreign element for the token, in the SVG namespace.
If the token has its self-closing flag set, pop the current node off the stack of open elements and acknowledge the token's self-closing flag.
Otherwise, if the insertion mode is not already "in foreign content", let the secondary insertion mode be the current insertion mode, and then switch the insertion mode to "in foreign content".
Parse error. Ignore the token.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
This element will be a phrasing element.
Run the following steps:
Initialize node to be the current node (the bottommost node of the stack).
If node has the same tag name as the end tag token, then:
If the tag name of the end tag token does not match the tag name of the current node, this is a parse error.
Pop all the nodes from the current node up to node, including node, then stop these steps.
Otherwise, if node is in neither the formatting category nor the phrasing category, then this is a parse error; ignore the token, and abort these steps.
Set node to the previous entry in the stack of open elements.
Return to step 2.
When the insertion mode is "in CDATA/RCDATA", tokens must be handled as follows:
Insert the token's character into the current node.
If the current node is a script
element, mark the script element as "already
executed".
Pop the current node off the stack of open elements.
Switch the insertion mode to the original insertion mode and reprocess the current token.
Let script be the current node
(which will be a script element).
Pop the current node off the stack of open elements.
Switch the insertion mode to the original insertion mode.
Let the old insertion point have the same value as the current insertion point. Let the insertion point be just before the next input character.
Increment the parser's script nesting level by one.
Run the script. This might cause some script to execute, which might cause new characters to be inserted into the tokenizer, and might cause the tokenizer to output more tokens, resulting in a reentrant invocation of the parser.
Decrement the parser's script nesting level by one. If the parser's script nesting level is zero, then set the parser pause flag to false.
Let the insertion point have the value of the old insertion point. (In other words, restore the insertion point to its previous value. This value might be the "undefined" value.)
At this stage, if there is a pending external script, then:
document.write():Set the parser pause flag to true, and abort the processing of any nested invocations of the tokenizer, yielding control back to the caller. (Tokenization will resume when the caller returns to the "outer" tree construction stage.)
Follow these steps:
Let the script be the pending external script. There is no longer a pending external script.
Pause until the script has completed loading.
Let the insertion point be just before the next input character.
Let the insertion point be undefined again.
If there is once again a pending external script, then repeat these steps from step 1.
Pop the current node off the stack of open elements.
Switch the insertion mode to the original insertion mode.
When the insertion mode is "in table", tokens must be handled as follows:
If the current table is tainted, then act as described in the "anything else" entry below.
Otherwise, insert the character into the current node.
Append a Comment node to the current
node with the data attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Clear the stack back to a table context. (See below.)
Insert a marker at the end of the list of active formatting elements.
Insert an HTML element for the token, then switch the insertion mode to "in caption".
Clear the stack back to a table context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in column group".
Act as if a start tag token with the tag name "colgroup" had been seen, then reprocess the current token.
Clear the stack back to a table context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in table body".
Act as if a start tag token with the tag name "tbody" had been seen, then reprocess the current token.
Parse error. Act as if an end tag token with the tag name "table" had been seen, then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the fragment case.
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token. (fragment case)
Otherwise:
Pop elements from this stack until a table
element has been popped from the stack.
Parse error. Ignore the token.
If the current table is tainted then act as described in the "anything else" entry below.
Otherwise, process the token using the rules for the "in head" insertion mode.
If the token does not have an attribute with the name "type",
or if it does, but that attribute's value is not an ASCII
case-insensitive match for the string "hidden", or, if the current table is
tainted, then: act as described in the "anything
else" entry below.
Otherwise:
Insert an HTML element for the token.
Pop that input element off the stack of
open elements.
If the current node is not the root
html element, then this is a parse
error.
It can only be the current node in the fragment case.
Parse error. Process the token using the
rules for the "in
body" insertion mode, except that if the
current node is a table,
tbody, tfoot, thead, or
tr element, then, whenever a node would be inserted
into the current node, it must instead be foster parented.
When the steps above require the UA to clear the stack
back to a table context, it means that the UA must, while
the current node is not a table
element or an html element, pop elements from the
stack of open elements.
The current node being an
html element after this process is a fragment
case.
When the insertion mode is "in caption", tokens must be handled as follows:
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token. (fragment case)
Otherwise:
Now, if the current node is not a
caption element, then this is a parse
error.
Pop elements from this stack until a caption
element has been popped from the stack.
Clear the list of active formatting elements up to the last marker.
Switch the insertion mode to "in table".
Parse error. Act as if an end tag with the tag name "caption" had been seen, then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the fragment case.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
When the insertion mode is "in column group", tokens must be handled as follows:
Insert the character into the current node.
Append a Comment node to the current
node with the data attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
If the current node is the root
html element, then this is a parse
error; ignore the token. (fragment
case)
Otherwise, pop the current node (which will be
a colgroup element) from the stack of open
elements. Switch the insertion mode to
"in table".
Parse error. Ignore the token.
If the current node is the root html
element, then stop parsing. (fragment
case)
Otherwise, act as described in the "anything else" entry below.
Act as if an end tag with the tag name "colgroup" had been seen, and then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the fragment case.
When the insertion mode is "in table body", tokens must be handled as follows:
Clear the stack back to a table body context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in row".
Parse error. Act as if a start tag with the tag name "tr" had been seen, then reprocess the current token.
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token.
Otherwise:
Clear the stack back to a table body context. (See below.)
Pop the current node from the stack of open elements. Switch the insertion mode to "in table".
If the stack of open elements does not have a
tbody, thead, or tfoot
element in table scope, this is a parse
error. Ignore the token. (fragment
case)
Otherwise:
Clear the stack back to a table body context. (See below.)
Act as if an end tag with the same tag name as the current node ("tbody", "tfoot", or "thead") had been seen, then reprocess the current token.
Parse error. Ignore the token.
Process the token using the rules for the "in table" insertion mode.
When the steps above require the UA to clear the stack
back to a table body context, it means that the UA must,
while the current node is not a tbody,
tfoot, thead, or html
element, pop elements from the stack of open
elements.
The current node being an
html element after this process is a fragment
case.
When the insertion mode is "in row", tokens must be handled as follows:
Clear the stack back to a table row context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in cell".
Insert a marker at the end of the list of active formatting elements.
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token. (fragment case)
Otherwise:
Clear the stack back to a table row context. (See below.)
Pop the current node (which will be a
tr element) from the stack of open
elements. Switch the insertion mode to
"in table
body".
Act as if an end tag with the tag name "tr" had been seen, then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the fragment case.
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token.
Otherwise, act as if an end tag with the tag name "tr" had been seen, then reprocess the current token.
Parse error. Ignore the token.
Process the token using the rules for the "in table" insertion mode.
When the steps above require the UA to clear the stack
back to a table row context, it means that the UA must,
while the current node is not a tr
element or an html element, pop elements from the
stack of open elements.
The current node being an
html element after this process is a fragment
case.
When the insertion mode is "in cell", tokens must be handled as follows:
If the stack of open elements does not have an element in table scope with the same tag name as that of the token, then this is a parse error and the token must be ignored.
Otherwise:
Now, if the current node is not an element with the same tag name as the token, then this is a parse error.
Pop elements from this stack until an element with the same tag name as the token has been popped from the stack.
Clear the list of active formatting elements up to the last marker.
Switch the insertion mode to "in row". (The
current node will be a tr element at
this point.)
If the stack of open elements does
not have
a td or th element in table
scope, then this is a parse error; ignore
the token. (fragment case)
Otherwise, close the cell (see below) and reprocess the current token.
Parse error. Ignore the token.
If the stack of open elements does not have an element in table scope with the same tag name as that of the token (which can only happen for "tbody", "tfoot" and "thead", or, in the fragment case), then this is a parse error and the token must be ignored.
Otherwise, close the cell (see below) and reprocess the current token.
Process the token using the rules for the "in body" insertion mode.
Where the steps above say to close the cell, they mean to run the following algorithm:
If the stack of open elements has a td
element in table scope, then act as if an end tag token
with the tag name "td" had been seen.
Otherwise, the stack of open elements will
have a
th element in table scope; act as if an end
tag token with the tag name "th" had been seen.
The stack of open elements cannot
have both a td and a th element in table scope at
the same time, nor can it have neither when the insertion
mode is "in
cell".
When the insertion mode is "in select", tokens must be handled as follows:
Insert the token's character into the current node.
Append a Comment node to the current
node with the data attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
If the current node is an option
element, act as if an end tag with the tag name "option" had
been seen.
Insert an HTML element for the token.
If the current node is an option
element, act as if an end tag with the tag name "option" had
been seen.
If the current node is an
optgroup element, act as if an end tag with the
tag name "optgroup" had been seen.
Insert an HTML element for the token.
First, if the current node is an
option element, and the node immediately before
it in the stack of open elements is an
optgroup element, then act as if an end tag with
the tag name "option" had been seen.
If the current node is an
optgroup element, then pop that node from the
stack of open elements. Otherwise, this is a
parse error; ignore the token.
If the current node is an option
element, then pop that node from the stack of open
elements. Otherwise, this is a parse
error; ignore the token.
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token. (fragment case)
Otherwise:
Pop elements from the stack of open elements
until a select element has been popped from the
stack.
Parse error. Act as if the token had been an end tag with the tag name "select" instead.
Parse error. Act as if an end tag with the tag name "select" had been seen, and reprocess the token.
Process the token using the rules for the "in head" insertion mode.
If the current node is not the root
html element, then this is a parse
error.
It can only be the current node in the fragment case.
Parse error. Ignore the token.
When the insertion mode is "in select in table", tokens must be handled as follows:
Parse error. Act as if an end tag with the tag name "select" had been seen, and reprocess the token.
If the stack of open elements has an element in table scope with the same tag name as that of the token, then act as if an end tag with the tag name "select" had been seen, and reprocess the token. Otherwise, ignore the token.
Process the token using the rules for the "in select" insertion mode.
When the insertion mode is "in foreign content", tokens must be handled as follows:
Insert the token's character into the current node.
Append a Comment node to the current
node with the data attribute set to
the data given in the comment token.
Parse error. Ignore the token.
script element in the SVG namespace.Pop the current node off the stack of open elements.
Let the old insertion point have the same value as the current insertion point. Let the insertion point be just before the next input character.
Increment the parser's script nesting level by one. Set the parser pause flag to true.
Process
the script element according to the SVG
rules. [SVG]
Even if this causes new characters to be inserted into the tokenizer, the parser will not be executed reentrantly, since the parser pause flag is true.
Decrement the parser's script nesting level by one. If the parser's script nesting level is zero, then set the parser pause flag to false.
Let the insertion point have the value of the old insertion point. (In other words, restore the insertion point to its previous value. This value might be the "undefined" value.)
mi element in the MathML namespace.mo element in the MathML namespace.mn element in the MathML namespace.ms element in the MathML namespace.mtext element in the MathML namespace.annotation-xml element in the MathML namespace.foreignObject element in the SVG namespace.desc element in the SVG namespace.title element in the SVG namespace.Process the token using the rules for the secondary insertion mode.
If, after doing so, the insertion mode is still "in foreign content", but there is no element in scope that has a namespace other than the HTML namespace, switch the insertion mode to the secondary insertion mode.
Pop elements from the stack of open elements until the current node is in the HTML namespace.
Switch the insertion mode to the secondary insertion mode, and reprocess the token.
If the current node is an element in the MathML namespace, adjust MathML attributes for the token. (This fixes the case of MathML attributes that are not all lowercase.)
If the current node is an element in the SVG namespace, and the token's tag name is one of the ones in the first column of the following table, change the tag name to the name given in the corresponding cell in the second column. (This fixes the case of SVG elements that are not all lowercase.)
| Tag name | Element name |
|---|---|
altglyph | altGlyph
|
altglyphdef | altGlyphDef
|
altglyphitem | altGlyphItem
|
animatecolor | animateColor
|
animatemotion | animateMotion
|
animatetransform | animateTransform
|
clippath | clipPath
|
feblend | feBlend
|
fecolormatrix | feColorMatrix
|
fecomponenttransfer | feComponentTransfer
|
fecomposite | feComposite
|
feconvolvematrix | feConvolveMatrix
|
fediffuselighting | feDiffuseLighting
|
fedisplacementmap | feDisplacementMap
|
fedistantlight | feDistantLight
|
feflood | feFlood
|
fefunca | feFuncA
|
fefuncb | feFuncB
|
fefuncg | feFuncG
|
fefuncr | feFuncR
|
fegaussianblur | feGaussianBlur
|
feimage | feImage
|
femerge | feMerge
|
femergenode | feMergeNode
|
femorphology | feMorphology
|
feoffset | feOffset
|
fepointlight | fePointLight
|
fespecularlighting | feSpecularLighting
|
fespotlight | feSpotLight
|
fetile | feTile
|
feturbulence | feTurbulence
|
foreignobject | foreignObject
|
glyphref | glyphRef
|
lineargradient | linearGradient
|
radialgradient | radialGradient
|
textpath | textPath
|
If the current node is an element in the SVG namespace, adjust SVG attributes for the token. (This fixes the case of SVG attributes that are not all lowercase.)
Adjust foreign attributes for the token. (This fixes the use of namespaced attributes, in particular XLink in SVG.)
Insert a foreign element for the token, in the same namespace as the current node.
If the token has its self-closing flag set, pop the current node off the stack of open elements and acknowledge the token's self-closing flag.
When the insertion mode is "after body", tokens must be handled as follows:
Process the token using the rules for the "in body" insertion mode.
Append a Comment node to the first element in
the stack of open elements (the html
element), with the data attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
If the parser was originally created as part of the HTML fragment parsing algorithm, this is a parse error; ignore the token. (fragment case)
Otherwise, switch the insertion mode to "after after body".
Parse error. Switch the insertion mode to "in body" and reprocess the token.
When the insertion mode is "in frameset", tokens must be handled as follows:
Insert the character into the current node.
Append a Comment node to the current
node with the data attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Insert an HTML element for the token.
If the current node is the root
html element, then this is a parse
error; ignore the token. (fragment
case)
Otherwise, pop the current node from the stack of open elements.
If the parser was not originally created as part
of the HTML fragment parsing algorithm
(fragment case), and the current
node is no longer a frameset element, then
switch the insertion mode to "after
frameset".
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
Process the token using the rules for the "in head" insertion mode.
If the current node is not the root
html element, then this is a parse
error.
It can only be the current node in the fragment case.
Parse error. Ignore the token.
When the insertion mode is "after frameset", tokens must be handled as follows:
Insert the character into the current node.
Append a Comment node to the current
node with the data attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Switch the insertion mode to "after after frameset".
Process the token using the rules for the "in head" insertion mode.
Parse error. Ignore the token.
This doesn't handle UAs that don't support frames, or that do support frames but want to show the NOFRAMES content. Supporting the former is easy; supporting the latter is harder.
When the insertion mode is "after after body", tokens must be handled as follows:
Append a Comment node to the Document
object with the data attribute set to the
data given in the comment token.
Process the token using the rules for the "in body" insertion mode.
Parse error. Switch the insertion mode to "in body" and reprocess the token.
When the insertion mode is "after after frameset", tokens must be handled as follows:
Append a Comment node to the Document
object with the data attribute set to the
data given in the comment token.
Process the token using the rules for the "in body" insertion mode.
Process the token using the rules for the "in head" insertion mode.
Parse error. Ignore the token.
Once the user agent stops parsing the document, the user agent must follow the steps in this section.
First, the current document readiness must be set to "interactive".
Then, the rules for when a script completes loading start applying (script execution is no longer managed by the parser).
If any of the scripts in the list of scripts that will
execute as soon as possible have completed
loading, or if the list of scripts that will execute
asynchronously is not empty and the first script in that list
has completed loading, then the user agent must act as
if those scripts just completed loading, following the rules given
for that in the script element definition.
Then, if the list of scripts that will execute when the document has finished parsing is not empty, and the first item in this list has already completed loading, then the user agent must act as if that script just finished loading.
By this point, there will be no scripts that have loaded but have not yet been executed.
The user agent must then fire a simple event called
DOMContentLoaded at the
Document.
Once everything that delays the load event has completed, the user agent must run the following steps:
Document is in a browsing
context, then queue a task to fire a load
event at the Document's Window
object.Document has a pending state
object, then queue a task to fire a popstate event in no namespace on the
Document's Window object using the
PopStateEvent interface, with the state attribute set to the
current value of the pending state object. This event
must bubble but not be cancelable and has no default action.The task source for these tasks is the DOM manipulation task source.
delaying the load event for things like image loads allows for intranet port scans (even without javascript!). Should we really encode that into the spec?
When an application uses an HTML parser in
conjunction with an XML pipeline, it is possible that the
constructed DOM is not compatible with the XML tool chain in certain
subtle ways. For example, an XML toolchain might not be able to
represent attributes with the name xmlns,
since they conflict with the Namespaces in XML syntax. There is also
some data that the HTML parser generates that isn't
included in the DOM itself. This section specifies some rules for
handling these issues.
If the XML API being used doesn't support DOCTYPEs, the tool may drop DOCTYPEs altogether.
If the XML API doesn't support attributes in no namespace that
are named "xmlns", attributes whose names
start with "xmlns:", or attributes in the
XMLNS namespace, then the tool may drop such
attributes.
The tool may annotate the output with any namespace declarations required for proper operation.
If the XML API being used restricts the allowable characters in the local names of elements and attributes, then the tool may map all element and attribute local names that the API wouldn't support to a set of names that are allowed, by replacing any character that isn't supported with the uppercase letter U and the six digits of the character's Unicode code point when expressed in hexadecimal, using digits 0-9 and capital letters A-F as the symbols, in increasing numeric order.
For example, the element name foo<bar, which can be output by the HTML
parser, though it is neither a legal HTML element name nor a
well-formed XML element name, would be converted into fooU00003Cbar, which is a well-formed XML
element name (though it's still not legal in HTML by any means).
As another example, consider the attribute
xlink:href. Used on a MathML element, it becomes, after
being adjusted, an
attribute with a prefix "xlink" and a local
name "href". However, used on an HTML element,
it becomes an attribute with no prefix and the local name "xlink:href", which is not a valid NCName, and thus
might not be accepted by an XML API. It could thus get converted,
becoming "xlinkU00003Ahref".
The resulting names from this conversion conveniently can't clash with any attribute generated by the HTML parser, since those are all either lowercase or those listed in the adjust foreign attributes algorithm's table.
If the XML API restricts comments from having two consecutive U+002D HYPHEN-MINUS characters (--), the tool may insert a single U+0020 SPACE character between any such offending characters.
If the XML API restricts comments from ending in a U+002D HYPHEN-MINUS character (-), the tool may insert a single U+0020 SPACE character at the end of such comments.
If the XML API restricts allowed characters in character data, the tool may replace any U+000C FORM FEED (FF) character with a U+0020 SPACE character, and any other literal non-XML character with a U+FFFD REPLACEMENT CHARACTER.
If the tool has no way to convey out-of-band information, then the tool may drop the following information:
form element ancestor (use of the
form element pointer in the parser)The mutations allowed by this section apply
after the HTML parser's rules have been
applied. For example, a <a::> start tag
will be closed by a </a::> end tag, and
never by a </aU00003AU00003A> end tag, even
if the user agent is using the rules above to then generate an
actual element in the DOM with the name aU00003AU00003A for that start tag.
The HTML namespace is: http://www.w3.org/1999/xhtml
The MathML namespace is: http://www.w3.org/1998/Math/MathML
The SVG namespace is: http://www.w3.org/2000/svg
The XLink namespace is: http://www.w3.org/1999/xlink
The XML namespace is: http://www.w3.org/XML/1998/namespace
The XMLNS namespace is: http://www.w3.org/2000/xmlns/
Data mining tools and other user agents that perform operations
on text/html content without running scripts,
evaluating CSS or XPath expressions, or otherwise exposing the
resulting DOM to arbitrary content, may "support namespaces" by just
asserting that their DOM node analogues are in certain namespaces,
without actually exposing the above strings.
The following steps form the HTML fragment serialization
algorithm. The algorithm takes as input a DOM
Element or Document, referred to as the node, and either returns a string or raises an
exception.
This algorithm serializes the children of the node being serialized, not the node itself.
Let s be a string, and initialize it to the empty string.
For each child node of the node, in tree order, run the following steps:
Let current node be the child node being processed.
Append the appropriate string from the following list to s:
ElementAppend a U+003C LESS-THAN SIGN (<)
character, followed by the element's tag name. (For nodes
created by the HTML parser or Document.createElement(), the tag name will be
lowercase.)
For each attribute that the element has, append a U+0020
SPACE character, the attribute's name (which, for attributes
set by the HTML parser or by Element.setAttributeNode() or Element.setAttribute(), will be lowercase), a
U+003D EQUALS SIGN (=) character, a
U+0022 QUOTATION MARK (")
character, the attribute's value, escaped as described below in attribute
mode, and a second U+0022 QUOTATION MARK (") character.
While the exact order of attributes is UA-defined, and may depend on factors such as the order that the attributes were given in the original markup, the sort order must be stable, such that consecutive invocations of this algorithm serialize an element's attributes in the same order.
Append a U+003E GREATER-THAN SIGN (>)
character.
If current node is an
area, base, basefont,
bgsound, br, col,
embed, frame, hr,
img, input, keygen,
link, meta, param,
spacer, or wbr element, then
continue on to the next child node at this point.
If current node is a pre,
textarea, or listing element, append
a U+000A LINE FEED (LF) character.
Append the value of running the HTML fragment
serialization algorithm on the current
node element (thus recursing into this algorithm for
that element), followed by a U+003C LESS-THAN SIGN (<) character, a U+002F SOLIDUS (/) character, the element's tag name again,
and finally a U+003E GREATER-THAN SIGN (>) character.
Text or CDATASection
nodeIf one of the ancestors of current node
is a style, script,
xmp, iframe, noembed,
noframes, noscript, or
plaintext element, then append the value of current node's data DOM
attribute literally.
Otherwise, append the value of current
node's data DOM attribute, escaped as described
below.
CommentAppend the literal string <!-- (U+003C
LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+002D HYPHEN-MINUS,
U+002D HYPHEN-MINUS), followed by the value of current node's data DOM
attribute, followed by the literal string -->
(U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS, U+003E GREATER-THAN
SIGN).
ProcessingInstructionAppend the literal string <? (U+003C
LESS-THAN SIGN, U+003F QUESTION MARK), followed by the value
of current node's target DOM attribute, followed by a single
U+0020 SPACE character, followed by the value of current node's data DOM
attribute, followed by a single U+003E GREATER-THAN SIGN
character ('>').
DocumentTypeAppend the literal string <!DOCTYPE (U+003C
LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+0044 LATIN CAPITAL
LETTER D, U+004F LATIN CAPITAL LETTER O, U+0043 LATIN CAPITAL
LETTER C, U+0054 LATIN CAPITAL LETTER T, U+0059 LATIN CAPITAL
LETTER Y, U+0050 LATIN CAPITAL LETTER P, U+0045 LATIN CAPITAL
LETTER E), followed by a space (U+0020 SPACE), followed by the
value of current node's name DOM attribute, followed by the literal
string > (U+003E GREATER-THAN SIGN).
Other node types (e.g. Attr) cannot
occur as children of elements. If, despite this, they somehow do
occur, this algorithm must raise an
INVALID_STATE_ERR exception.
The result of the algorithm is the string s.
Escaping a string (for the
purposes of the algorithm above) consists of replacing any
occurrences of the "&" character by the
string "&", any occurrences of the
U+00A0 NO-BREAK SPACE character by the string " ", and, if the algorithm was invoked in
the attribute mode, any occurrences of the """ character by the string """, or if it was not, any occurrences of
the "<" character by the string "<", any occurrences of the ">" character by the string ">".
Entity reference nodes are assumed to be expanded by the user agent, and are therefore not covered in the algorithm above.
It is possible that the output of this algorithm, if
parsed with an HTML parser, will not return the
original tree structure. For instance, if a textarea
element to which a Comment node has been
appended is serialized and the output is then reparsed, the comment
will end up being displayed in the text field. Similarly, if, as a
result of DOM manipulation, an element contains a comment that
contains the literal string "-->", then
when the result of serializing the element is parsed, the comment
will be truncated at that point and the rest of the comment will be
interpreted as markup. More examples would be making a
script element contain a text node with the text string
"</script>", or having a p element that
contains a ul element (as the ul element's
start tag would imply the end
tag for the p).
The following steps form the HTML fragment parsing
algorithm. The algorithm optionally takes as input an
Element node, referred to as the context element, which gives the context for the
parser, as well as input, a string to parse, and
returns a list of zero or more nodes.
Parts marked fragment case in algorithms in the parser section are parts that only occur if the parser was created for the purposes of this algorithm (and with a context element). The algorithms have been annotated with such markings for informational purposes only; such markings have no normative weight. If it is possible for a condition described as a fragment case to occur even when the parser wasn't created for the purposes of handling this algorithm, then that is an error in the specification.
Create a new Document node, and mark it as being
an HTML document.
If there is a context element, and the
Document of the context element
is in quirks mode, then let the Document
be in quirks mode. Otherwise, if there is a context element, and the Document of
the context element is in limited quirks
mode, then let the Document be in
limited quirks mode. Otherwise, leave the
Document in no quirks mode.
Create a new HTML parser, and associate it with
the just created Document node.
If there is a context element, run these substeps:
Set the HTML parser's tokenization stage's content model flag according to the context element, as follows:
title or textarea
elementstyle, script,
xmp, iframe, noembed, or
noframes elementnoscript elementplaintext elementLet root be a new html element
with no attributes.
Append the element root to the
Document node created above.
Set up the parser's stack of open elements so that it contains just the single element root.
Reset the parser's insertion mode appropriately.
The parser will reference the context element as part of that algorithm.
Set the parser's form element pointer
to the nearest node to the context element
that is a form element (going straight up the
ancestor chain, and including the element itself, if it is a
form element), or, if there is no such
form element, to null.
Place into the input stream for the HTML parser just created the input. The encoding confidence is irrelevant.
Start the parser and let it run until it has consumed all the characters just inserted into the input stream.
If there is a context element, return the child nodes of root, in tree order.
Otherwise, return the children of the Document
object, in tree order.