← 4.10.7.2 Common input element attributesTable of contents4.10.18 Association of controls and forms →
      1. 4.10.8 The button element
      2. 4.10.9 The select element
      3. 4.10.10 The datalist element
      4. 4.10.11 The optgroup element
      5. 4.10.12 The option element
      6. 4.10.13 The textarea element
      7. 4.10.14 The keygen element
      8. 4.10.15 The output element
      9. 4.10.16 The progress element
      10. 4.10.17 The meter element

4.10.8 The button element

Categories
Flow content.
Phrasing content.
Interactive content.
Listed, labelable, and submittable form-associated element.
Contexts in which this element can be used:
Where phrasing content is expected.
Content model:
Phrasing content, but there must be no interactive content descendant.
Content attributes:
Global attributes
autofocus
disabled
form
formaction
formenctype
formmethod
formnovalidate
formtarget
name
type
value
DOM interface:
interface HTMLButtonElement : HTMLElement {
           attribute boolean autofocus;
           attribute boolean disabled;
  readonly attribute HTMLFormElement form;
           attribute DOMString formAction;
           attribute DOMString formEnctype;
           attribute DOMString formMethod;
           attribute DOMString formNoValidate;
           attribute DOMString formTarget;
           attribute DOMString name;
           attribute DOMString type;
           attribute DOMString value;

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);

  readonly attribute NodeList labels;
};

The button element represents a button. If the element is not disabled, then the user agent should allow the user to activate the button.

The element is a button.

The type attribute controls the behavior of the button when it is activated. It is an enumerated attribute. The following table lists the keywords and states for the attribute — the keywords in the left column map to the states in the cell in the second column on the same row as the keyword.

Keyword State Brief description
submit Submit Button Submits the form.
reset Reset Button Resets the form.
button Button Does nothing.

The missing value default is the Submit Button state.

If the type attribute is in the Submit Button state, the element is specifically a submit button.

Constraint validation: If the type attribute is in the Reset Button state or the Button state, the element is barred from constraint validation.

If the element is not disabled, the activation behavior of the button element is to run the steps defined in the following list for the current state of the element's type attribute.

Submit Button

If the element has a form owner, the element must submit the form owner from the button element.

Reset Button

If the element has a form owner, the element must reset the form owner.

Button

Do nothing.

The form attribute is used to explicitly associate the button element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus. The formaction, formenctype, formmethod, formnovalidate, and formtarget attributes are attributes for form submission.

The formnovalidate attribute can be used to make submit buttons that do not trigger the constraint validation.

The formaction, formenctype, formmethod, formnovalidate, and formtarget must not be specified if the element's type attribute is not in the Submit Button state.

The value attribute gives the element's value for the purposes of form submission. The element's value is the value of the element's value attribute, if there is one, or the empty string otherwise.

A button (and its value) is only included in the form submission if the button itself was used to initiate the form submission.

The value IDL attribute must reflect the content attribute of the same name.

The type IDL attribute must reflect the content attribute of the same name, limited to only known values.

The willValidate, validity, and validationMessage attributes, and the checkValidity() and setCustomValidity() methods, are part of the constraint validation API. The labels attribute provides a list of the element's labels. The autofocus, disabled, form, and name IDL attributes are part of the element's forms API.

The following button is labeled "Show hint" and pops up a dialog box when activated:

<button type=button
        onclick="alert('This 15-20 minute piece was composed by George Gershwin.')">
 Show hint
</button>

4.10.9 The select element

Categories
Flow content.
Phrasing content.
Interactive content.
Listed, labelable, submittable, and resettable form-associated element.
Contexts in which this element can be used:
Where phrasing content is expected.
Content model:
Zero or more option or optgroup elements.
Content attributes:
Global attributes
autofocus
disabled
form
multiple
name
required
size
DOM interface:
interface HTMLSelectElement : HTMLElement {
           attribute boolean autofocus;
           attribute boolean disabled;
  readonly attribute HTMLFormElement form;
           attribute boolean multiple;
           attribute DOMString name;
           attribute boolean required;
           attribute unsigned long size;

  readonly attribute DOMString type;

  readonly attribute HTMLOptionsCollection options;
           attribute unsigned long length;
  getter any item(in unsigned long index);
  any namedItem(in DOMString name);
  void add(in HTMLElement element, in optional HTMLElement before);
  void add(in HTMLElement element, in long before);
  void remove(in long index);

  readonly attribute HTMLCollection selectedOptions;
           attribute long selectedIndex;
           attribute DOMString value;

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);

  readonly attribute NodeList labels;
};

The select element represents a control for selecting amongst a set of options.

The multiple attribute is a boolean attribute. If the attribute is present, then the select element represents a control for selecting zero or more options from the list of options. If the attribute is absent, then the select element represents a control for selecting a single option from the list of options.

The size attribute gives the number of options to show to the user. The size attribute, if specified, must have a value that is a valid non-negative integer greater than zero. If the multiple attribute is present, then the size attribute's default value is 4. If the multiple attribute is absent, then the size attribute's default value is 1.

The display size of a select element is the result of applying the rules for parsing non-negative integers to the value of element's size attribute, if it has one and parsing it is successful. If applying those rules to the attribute's value is not successful, or if the size attribute is absent, the element's display size is the default value of the attribute.

The list of options for a select element consists of all the option element children of the select element, and all the option element children of all the optgroup element children of the select element, in tree order.

The required attribute is a boolean attribute. When specified, the user will be required to select a value before submitting the form.

If a select element has a required attribute specified, does not have a multiple attribute specified, and has a display size of 1; and if the value of the first option element in the select element's list of options (if any) is the empty string, and that option is not disabled, and, finally, that option element's parent node is the select element (and not an optgroup element), then that option is the select element's placeholder label option.

Constraint validation: If the element has its required attribute specified, and either none of the option elements in the select element's list of options have their selectedness set to true, or the only option element in the selected element's list of options with its selectedness set to true is the placeholder label option, then the element is suffering from being missing.

If the multiple attribute is absent, and the element is not disabled, then the user agent should allow the user to pick an option element in its list of options that is itself not disabled. Upon this option element being picked (either through a click, or through unfocusing the element after changing its value, or through a menu command, or through any other mechanism), and before the relevant user interaction event is queued (e.g. before the click event), the user agent must set the selectedness of the picked option element to true and then queue a task to fire a simple event that bubbles named change at the select element, using the user interaction task source as the task source, then broadcast formchange events at the element's form owner.

If the multiple attribute is absent, whenever an option element in the select element's list of options has its selectedness set to true, and whenever an option element with its selectedness set to true is added to the select element's list of options, the user agent must set the selectedness of all the other option element in its list of options to false.

If the multiple attribute is absent and the element's display size is greater than 1, then the user agent should also allow the user to request that the option whose selectedness is true, if any, be unselected. Upon this request being conveyed to the user agent, and before the relevant user interaction event is queued (e.g. before the click event), the user agent must set the selectedness of that option element to false and then queue a task to fire a simple event that bubbles named change at the select element, using the user interaction task source as the task source, then broadcast formchange events at the element's form owner.

If the multiple attribute is absent and the element's display size is 1, then whenever there are no option elements in the select element's list of options that have their selectedness set to true, the user agent must set the selectedness of the first option element in the list of options in tree order that is not disabled, if any, to true.

If the multiple attribute is present, and the element is not disabled, then the user agent should allow the user to toggle the selectedness of the option elements in its list of options that are themselves not disabled (either through a click, or through a menu command, or any other mechanism). Upon the selectedness of one or more option elements being changed by the user, and before the relevant user interaction event is queued (e.g. before a related click event), the user agent must queue a task to fire a simple event that bubbles named change at the select element, using the user interaction task source as the task source, then broadcast formchange events at the element's form owner.

The reset algorithm for select elements is to go through all the option elements in the element's list of options, and set their selectedness to true if the option element has a selected attribute, and false otherwise.

The form attribute is used to explicitly associate the select element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus.

select . type

Returns "select-multiple" if the element has a multiple attribute, and "select-one" otherwise.

select . options

Returns an HTMLOptionsCollection of the list of options.

select . length [ = value ]

Returns the number of elements in the list of options.

When set to a smaller number, truncates the number of option elements in the select.

When set to a greater number, adds new blank option elements to the select.

element = select . item(index)
select[index]

Returns the item with index index from the list of options. The items are sorted in tree order.

Returns null if index is out of range.

element = select . namedItem(name)

Returns the item with ID or name name from the list of options.

If there are multiple matching items, then a NodeList object containing all those elements is returned.

Returns null if no element with that ID could be found.

select . add(element [, before ])

Inserts element before the node given by before.

The before argument can be a number, in which case element is inserted before the item with that number, or an element from the list of options, in which case element is inserted before that element.

If before is omitted, null, or a number out of range, then element will be added at the end of the list.

This method will throw a HIERARCHY_REQUEST_ERR exception if element is an ancestor of the element into which it is to be inserted. If element is not an option or optgroup element, then the method does nothing.

select . selectedOptions

Returns an HTMLCollection of the list of options that are selected.

select . selectedIndex [ = value ]

Returns the index of the first selected item, if any, or −1 if there is no selected item.

Can be set, to change the selection.

select . value [ = value ]

Returns the value of the first selected item, if any, or the empty string if there is no selected item.

Can be set, to change the selection.

The type IDL attribute, on getting, must return the string "select-one" if the multiple attribute is absent, and the string "select-multiple" if the multiple attribute is present.

The options IDL attribute must return an HTMLOptionsCollection rooted at the select node, whose filter matches the elements in the list of options.

The options collection is also mirrored on the HTMLSelectElement object. The supported property indices at any instant are the indices supported by the object returned by the options attribute at that instant.

The length IDL attribute must return the number of nodes represented by the options collection. On setting, it must act like the attribute of the same name on the options collection.

The item(index) method must return the value returned by the method of the same name on the options collection, when invoked with the same argument.

The namedItem(name) method must return the value returned by the method of the same name on the options collection, when invoked with the same argument.

Similarly, the add() and remove() methods must act like their namesake methods on that same options collection.

The selectedOptions IDL attribute must return an HTMLCollection rooted at the select node, whose filter matches the elements in the list of options that have their selectedness set to true.

The selectedIndex IDL attribute, on getting, must return the index of the first option element in the list of options in tree order that has its selectedness set to true, if any. If there isn't one, then it must return −1.

On setting, the selectedIndex attribute must set the selectedness of all the option elements in the list of options to false, and then the option element in the list of options whose index is the given new value, if any, must have its selectedness set to true.

The value IDL attribute, on getting, must return the value of the first option element in the list of options in tree order that has its selectedness set to true, if any. If there isn't one, then it must return the empty string.

On setting, the value attribute must set the selectedness of all the option elements in the list of options to false, and then the first option element in the list of options, in tree order, whose value is equal to the given new value, if any, must have its selectedness set to true.

The multiple, required, and size IDL attributes must reflect the respective content attributes of the same name. The size IDL attribute is limited to only non-negative numbers greater than zero, and has no default value (unlike the size content attribute that it reflects).

The willValidate, validity, and validationMessage attributes, and the checkValidity() and setCustomValidity() methods, are part of the constraint validation API. The labels attribute provides a list of the element's labels. The autofocus, disabled, form, and name IDL attributes are part of the element's forms API.

The following example shows how a select element can be used to offer the user with a set of options from which the user can select a single option. The default option is preselected.

<p>
 <label for="unittype">Select unit type:</label>
 <select id="unittype" name="unittype">
  <option value="1"> Miner </option>
  <option value="2"> Puffer </option>
  <option value="3" selected> Snipey </option>
  <option value="4"> Max </option>
  <option value="5"> Firebot </option>
 </select>
</p>

Here, the user is offered a set of options from which he can select any number. By default, all five options are selected.

<p>
 <label for="allowedunits">Select unit types to enable on this map:</label>
 <select id="allowedunits" name="allowedunits" multiple>
  <option value="1" selected> Miner </option>
  <option value="2" selected> Puffer </option>
  <option value="3" selected> Snipey </option>
  <option value="4" selected> Max </option>
  <option value="5" selected> Firebot </option>
 </select>
</p>

4.10.10 The datalist element

Categories
Flow content.
Phrasing content.
Contexts in which this element can be used:
Where phrasing content is expected.
Content model:
Either: phrasing content.
Or: Zero or more option elements.
Content attributes:
Global attributes
DOM interface:
interface HTMLDataListElement : HTMLElement {
  readonly attribute HTMLCollection options;
};

The datalist element represents a set of option elements that represent predefined options for other controls. The contents of the element represents fallback content for legacy user agents, intermixed with option elements that represent the predefined options. In the rendering, the datalist element represents nothing and it, along with its children, should be hidden.

The datalist element is hooked up to an input element using the list attribute on the input element.

Each option element that is a descendant of the datalist element, that is not disabled, and whose value is a string that isn't the empty string, represents a suggestion. Each suggestion has a value and a label.

datalist . options

Returns an HTMLCollection of the options elements of the table.

The options IDL attribute must return an HTMLCollection rooted at the datalist node, whose filter matches option elements.

Constraint validation: If an element has a datalist element ancestor, it is barred from constraint validation.

4.10.11 The optgroup element

Categories
None.
Contexts in which this element can be used:
As a child of a select element.
Content model:
Zero or more option elements.
Content attributes:
Global attributes
disabled
label
DOM interface:
interface HTMLOptGroupElement : HTMLElement {
           attribute boolean disabled;
           attribute DOMString label;
};

The optgroup element represents a group of option elements with a common label.

The element's group of option elements consists of the option elements that are children of the optgroup element.

When showing option elements in select elements, user agents should show the option elements of such groups as being related to each other and separate from other option elements.

The disabled attribute is a boolean attribute and can be used to disable a group of option elements together.

The label attribute must be specified. Its value gives the name of the group, for the purposes of the user interface. User agents should use this attribute's value when labelling the group of option elements in a select element.

The disabled and label attributes must reflect the respective content attributes of the same name.

The following snippet shows how a set of lessons from three courses could be offered in a select drop-down widget:

<form action="courseselector.dll" method="get">
 <p>Which course would you like to watch today?
 <p><label>Course:
  <select name="c">
   <optgroup label="8.01 Physics I: Classical Mechanics">
    <option value="8.01.1">Lecture 01: Powers of Ten
    <option value="8.01.2">Lecture 02: 1D Kinematics
    <option value="8.01.3">Lecture 03: Vectors
   <optgroup label="8.02 Electricity and Magnestism">
    <option value="8.02.1">Lecture 01: What holds our world together?
    <option value="8.02.2">Lecture 02: Electric Field
    <option value="8.02.3">Lecture 03: Electric Flux
   <optgroup label="8.03 Physics III: Vibrations and Waves">
    <option value="8.03.1">Lecture 01: Periodic Phenomenon
    <option value="8.03.2">Lecture 02: Beats
    <option value="8.03.3">Lecture 03: Forced Oscillations with Damping
  </select>
 </label>
 <p><input type=submit value="▶ Play">
</form>

4.10.12 The option element

Categories
None.
Contexts in which this element can be used:
As a child of a select element.
As a child of a datalist element.
As a child of an optgroup element.
Content model:
Text.
Content attributes:
Global attributes
disabled
label
selected
value
DOM interface:
[NamedConstructor=Option(),
 NamedConstructor=Option(in DOMString text),
 NamedConstructor=Option(in DOMString text, in DOMString value),
 NamedConstructor=Option(in DOMString text, in DOMString value, in boolean defaultSelected),
 NamedConstructor=Option(in DOMString text, in DOMString value, in boolean defaultSelected, in boolean selected)]
interface HTMLOptionElement : HTMLElement {
           attribute boolean disabled;
  readonly attribute HTMLFormElement form;
           attribute DOMString label;
           attribute boolean defaultSelected;
           attribute boolean selected;
           attribute DOMString value;

           attribute DOMString text;
  readonly attribute long index;
};

The option element represents an option in a select element or as part of a list of suggestions in a datalist element.

In certain circumstances described in the definition of the select element, an option element can be a select element's placeholder label option. A placeholder label option does not represent an actual option, but instead represents a label for the select control.

The disabled attribute is a boolean attribute. An option element is disabled if its disabled attribute is present or if it is a child of an optgroup element whose disabled attribute is present.

An option element that is disabled must prevent any click events that are queued on the user interaction task source from being dispatched on the element.

The label attribute provides a label for element. The label of an option element is the value of the label attribute, if there is one, or the textContent of the element, if there isn't.

The value attribute provides a value for element. The value of an option element is the value of the value attribute, if there is one, or the textContent of the element, if there isn't.

The selected attribute is a boolean attribute. It represents the default selectedness of the element.

The selectedness of an option element is a boolean state, initially false. Except where otherwise specified, when the element is created, its selectedness must be set to true if the element has a selected attribute. Whenever an option element's selected attribute is added, its selectedness must be set to true.

The Option() constructor with three or fewer arguments overrides the initial state of the selectedness state to always be false even if the third argument is true (implying that a selected attribute is to be set). The fourth argument can be used to explicitly set the initial selectedness state when using the constructor.

A select element whose multiple attribute is not specified must not have more than one descendant option element with its selected attribute set.

An option element's index is the number of option element that are in the same list of options but that come before it in tree order. If the option element is not in a list of options, then the option element's index is zero.

option . selected

Returns true if the element is selected, and false otherwise.

Can be set, to override the current state of the element.

option . index

Returns the index of the element in its select element's options list.

option . form

Returns the element's form element, if any, or null otherwise.

option . text

Same as textContent, except that spaces are collapsed.

option = new Option( [ text [, value [, defaultSelected [, selected ] ] ] ] )

Returns a new option element.

The text argument sets the contents of the element.

The value argument sets the value attribute.

The defaultSelected argument sets the selected attribute.

The selected argument sets whether or not the element is selected. If it is omitted, even if the defaultSelected argument is true, the element is not selected.

The disabled and label IDL attributes must reflect the respective content attributes of the same name. The defaultSelected IDL attribute must reflect the selected content attribute.

The value IDL attribute, on getting, must return the value of the element's value content attribute, if it has one, or else the value of the element's textContent IDL attribute. On setting, the element's value content attribute must be set to the new value.

The selected IDL attribute, on getting, must return true if the element's selectedness is true, and false otherwise. On setting, it must set the element's selectedness to the new value.

The index IDL attribute must return the element's index.

The text IDL attribute, on getting, must return the value of the textContent IDL attribute on the element with leading and trailing space characters removed, and with any sequences of two or more space characters replaced by a single U+0020 SPACE character. On setting, it must act as if the textContent IDL attribute on the element had been set to the new value.

The form IDL attribute's behavior depends on whether the option element is in a select element or not. If the option has a select element as its parent, or has a colgroup element as its parent and that colgroup element has a select element as its parent, then the form IDL attribute must return the same value as the form IDL attribute on that select element. Otherwise, it must return null.

Several constructors are provided for creating HTMLOptionElement objects (in addition to the factory methods from DOM Core such as createElement()): Option(), Option(text), Option(text, value), Option(text, value, defaultSelected), and Option(text, value, defaultSelected, selected). When invoked as constructors, these must return a new HTMLOptionElement object (a new option element). If the text argument is present, the new object must have as its only child a Node with node type TEXT_NODE (3) whose data is the value of that argument. If the value argument is present, the new object must have a value attribute set with the value of the argument as its value. If the defaultSelected argument is present and true, the new object must have a selected attribute set with no value. If the selected argument is present and true, the new object must have its selectedness set to true; otherwise the fourth argument is absent or false, and the selectedness must be set to false, even if the defaultSelected argument is present and true. The element's document must be the active document of the browsing context of the Window object on which the interface object of the invoked constructor is found.

4.10.13 The textarea element

Categories
Flow content.
Phrasing content.
Interactive content.
Listed, labelable, submittable, and resettable form-associated element.
Contexts in which this element can be used:
Where phrasing content is expected.
Content model:
Text.
Content attributes:
Global attributes
autofocus
cols
disabled
form
maxlength
name
placeholder
readonly
required
rows
wrap
DOM interface:
interface HTMLTextAreaElement : HTMLElement {
           attribute boolean autofocus;
           attribute unsigned long cols;
           attribute boolean disabled;
  readonly attribute HTMLFormElement form;
           attribute long maxLength;
           attribute DOMString name;
           attribute DOMString placeholder;
           attribute boolean readOnly;
           attribute boolean required;
           attribute unsigned long rows;
           attribute DOMString wrap;

  readonly attribute DOMString type;
           attribute DOMString defaultValue;
           attribute DOMString value;
  readonly attribute unsigned long textLength;

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);

  readonly attribute NodeList labels;

  void select();
           attribute unsigned long selectionStart;
           attribute unsigned long selectionEnd;
  void setSelectionRange(in unsigned long start, in unsigned long end);
};

The textarea element represents a multiline plain text edit control for the element's raw value. The contents of the control represent the control's default value.

The raw value of a textarea control must be initially the empty string.

The readonly attribute is a boolean attribute used to control whether the text can be edited by the user or not.

Constraint validation: If the readonly attribute is specified on a textarea element, the element is barred from constraint validation.

A textarea element is mutable if it is neither disabled nor has a readonly attribute specified.

When a textarea is mutable, its raw value should be editable by the user. Any time the user causes the element's raw value to change, the user agent must queue a task to fire a simple event that bubbles named input at the textarea element, then broadcast forminput events at the textarea element's form owner. User agents may wait for a suitable break in the user's interaction before queuing the task; for example, a user agent could wait for the user to have not hit a key for 100ms, so as to only fire the event when the user pauses, instead of continuously for each keystroke.

A textarea element has a dirty value flag, which must be initially set to false, and must be set to true whenever the user interacts with the control in a way that changes the raw value.

When the textarea element's textContent IDL attribute changes value, if the element's dirty value flag is false, then the element's raw value must be set to the value of the element's textContent IDL attribute.

The reset algorithm for textarea elements is to set the element's value to the value of the element's textContent IDL attribute.

The cols attribute specifies the expected maximum number of characters per line. If the cols attribute is specified, its value must be a valid non-negative integer greater than zero. If applying the rules for parsing non-negative integers to the attribute's value results in a number greater than zero, then the element's character width is that value; otherwise, it is 20.

The user agent may use the textarea element's character width as a hint to the user as to how many characters the server prefers per line (e.g. for visual user agents by making the width of the control be that many characters). In visual renderings, the user agent should wrap the user's input in the rendering so that each line is no wider than this number of characters.

The rows attribute specifies the number of lines to show. If the rows attribute is specified, its value must be a valid non-negative integer greater than zero. If applying the rules for parsing non-negative integers to the attribute's value results in a number greater than zero, then the element's character height is that value; otherwise, it is 2.

Visual user agents should set the height of the control to the number of lines given by character height.

The wrap attribute is an enumerated attribute with two keywords and states: the soft keyword which maps to the Soft state, and the hard keyword which maps to the Hard state. The missing value default is the Soft state.

The Soft state indicates that the text in the textarea is not to be wrapped when it is submitted (though it can still be wrapped in the rendering).

The Hard state indicates that the text in the textarea is to have newlines added by the user agent so that the text is wrapped when it is submitted.

If the element's wrap attribute is in the Hard state, the cols attribute must be specified.

The element's value is defined to be the element's raw value with the following transformation applied:

  1. Replace every occurrence of a U+000D CARRIAGE RETURN (CR) character not followed by a U+000A LINE FEED (LF) character, and every occurrence of a U+000A LINE FEED (LF) character not preceded by a U+000D CARRIAGE RETURN (CR) character, by a two-character string consisting of a U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pair.

  2. If the element's wrap attribute is in the Hard state, insert U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pairs into the string using a UA-defined algorithm so that each line has no more than character width characters. For the purposes of this requirement, lines are delimited by the start of the string, the end of the string, and U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pairs.

The maxlength attribute is a form control maxlength attribute controlled by the textarea element's dirty value flag.

If the textarea element has a maximum allowed value length, then the element's children must be such that the code-point length of the value of the element's textContent IDL attribute is equal to or less than the element's maximum allowed value length.

The required attribute is a boolean attribute. When specified, the user will be required to enter a value before submitting the form.

Constraint validation: If the element has its required attribute specified, and the element is mutable, and the element's value is the empty string, then the element is suffering from being missing.

The placeholder attribute represents a hint (a word or short phrase) intended to aid the user with data entry. A hint could be a sample value or a brief description of the expected format. The attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.

For a longer hint or other advisory text, the title attribute is more appropriate.

The placeholder attribute should not be used as an alternative to a label.

User agents should present this hint to the user, after having stripped line breaks from it, when the element's value is the empty string and the control is not focused (e.g. by displaying it inside a blank unfocused control).

The form attribute is used to explicitly associate the textarea element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus.

textarea . type

Returns the string "textarea".

textarea . value

Returns the current value of the element.

Can be set, to change the value.

The cols, placeholder, required, rows, and wrap attributes must reflect the respective content attributes of the same name. The cols and rows attributes are limited to only non-negative numbers greater than zero. The cols attribute's default value is 20. The rows attribute's default value is 2. The maxLength IDL attribute must reflect the maxlength content attribute, limited to only non-negative numbers. The readOnly IDL attribute must reflect the readonly content attribute.

The type IDL attribute must return the value "textarea".

The defaultValue IDL attribute must act like the element's textContent IDL attribute.

The value attribute must, on getting, return the element's raw value; on setting, it must set the element's raw value to the new value.

The textLength IDL attribute must return the code-point length of the element's value.

The willValidate, validity, and validationMessage attributes, and the checkValidity() and setCustomValidity() methods, are part of the constraint validation API. The labels attribute provides a list of the element's labels. The select(), selectionStart, selectionEnd, and setSelectionRange() methods and attributes expose the element's text selection. The autofocus, disabled, form, and name IDL attributes are part of the element's forms API.

Here is an example of a textarea being used for unrestricted free-form text input in a form:

<p>If you have any comments, please let us know: <textarea cols=80 name=comments></textarea></p>

4.10.14 The keygen element

Categories
Flow content.
Phrasing content.
Interactive content.
Listed, labelable, submittable, and resettable form-associated element.
Contexts in which this element can be used:
Where phrasing content is expected.
Content model:
Empty.
Content attributes:
Global attributes
autofocus
challenge
disabled
form
keytype
name
DOM interface:
interface HTMLKeygenElement : HTMLElement {
           attribute boolean autofocus;
           attribute DOMString challenge;
           attribute boolean disabled;
  readonly attribute HTMLFormElement form;
           attribute DOMString keytype;
           attribute DOMString name;

  readonly attribute DOMString type;

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);

  readonly attribute NodeList labels;
};

The keygen element represents a key pair generator control. When the control's form is submitted, the private key is stored in the local keystore, and the public key is packaged and sent to the server.

The challenge attribute may be specified. Its value will be packaged with the submitted key.

The keytype attribute is an enumerated attribute. The following table lists the keywords and states for the attribute — the keywords in the left column map to the states listed in the cell in the second column on the same row as the keyword. User agents are not required to support these values, and must only recognize values whose corresponding algorithms they support.

Keyword State
rsa RSA

The invalid value default state is the unknown state. The missing value default state is the RSA state, if it is supported, or the unknown state otherwise.

This specification does not specify what key types user agents are to support — it is possible for a user agent to not support any key types at all.

The user agent may expose a user interface for each keygen element to allow the user to configure settings of the element's key pair generator, e.g. the key length.

The reset algorithm for keygen elements is to set these various configuration settings back to their defaults.

The element's value is the string returned from the following algorithm:

  1. Use the appropriate step from the following list:

    If the keytype attribute is in the RSA state

    Generate an RSA key pair using the settings given by the user, if appropriate, using the md5WithRSAEncryption RSA signature algorithm (the signature algorithm with MD5 and the RSA encryption algorithm) referenced in section 2.2.1 ("RSA Signature Algorithm") of RFC 3279, and defined in RFC 2313. [RFC3279] [RFC2313]

    Otherwise, the keytype attribute is in the unknown state

    The given key type is not supported. Return the empty string and abort this algorithm.

    Let private key be the generated private key.

    Let public key be the generated public key.

    Let signature algorithm be the selected signature algorithm.

  2. If the element has a challenge attribute, then let challenge be that attribute's value. Otherwise, let challenge be the empty string.

  3. Let algorithm be an ASN.1 AlgorithmIdentifier structure as defined by RFC 5280, with the algorithm field giving the ASN.1 OID used to identify signature algorithm, using the OIDs defined in section 2.2 ("Signature Algorithms") of RFC 3279, and the parameters field set up as required by RFC 3279 for AlgorithmIdentifier structures for that algorithm. [X690] [RFC5280] [RFC3279]

  4. Let spki be an ASN.1 SubjectPublicKeyInfo structure as defined by RFC 5280, with the algorithm field set to the algorithm structure from the previous step, and the subjectPublicKey field set to the BIT STRING value resulting from ASN.1 DER encoding the public key. [X690] [RFC5280]

  5. Let publicKeyAndChallenge be an ASN.1 PublicKeyAndChallenge structure as defined below, with the spki field set to the spki structure from the previous step, and the challenge field set to the string challenge obtained earlier. [X690]

  6. Let signature be the BIT STRING value resulting from ASN.1 DER encoding the signature generated by applying the signature algorithm to the byte string obtained by ASN.1 DER encoding the publicKeyAndChallenge structure, using private key as the signing key. [X690]

  7. Let signedPublicKeyAndChallenge be an ASN.1 SignedPublicKeyAndChallenge structure as defined below, with the publicKeyAndChallenge field set to the publicKeyAndChallenge structure, the signatureAlgorithm field set to the algorithm structure, and the signature field set to the BIT STRING signature from the previous step. [X690]

  8. Return the result of base64 encoding the result of ASN.1 DER encoding the signedPublicKeyAndChallenge structure. [RFC4648] [X690]

The data objects used by the above algorithm are defined as follows. These definitions use the same "ASN.1-like" syntax defined by RFC 5280. [RFC5280]

PublicKeyAndChallenge ::= SEQUENCE {
    spki SubjectPublicKeyInfo,
    challenge IA5STRING
}

SignedPublicKeyAndChallenge ::= SEQUENCE {
    publicKeyAndChallenge PublicKeyAndChallenge,
    signatureAlgorithm AlgorithmIdentifier,
    signature BIT STRING
}

Constraint validation: The keygen element is barred from constraint validation.

The form attribute is used to explicitly associate the keygen element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus.

keygen . type

Returns the string "keygen".

The challenge IDL attribute must reflect the content attribute of the same name.

The keytype IDL attribute must reflect the content attribute of the same name, limited to only known values.

The type IDL attribute must return the value "keygen".

The willValidate, validity, and validationMessage attributes, and the checkValidity() and setCustomValidity() methods, are part of the constraint validation API. The labels attribute provides a list of the element's labels. The autofocus, disabled, form, and name IDL attributes are part of the element's forms API.

This specification does not specify how the private key generated is to be used. It is expected that after receiving the SignedPublicKeyAndChallenge (SPKAC) structure, the server will generate a client certificate and offer it back to the user for download; this certificate, once downloaded and stored in the key store along with the private key, can then be used to authenticate to services that use TLS and certificate authentication.

To generate a key pair, add the private key to the user's key store, and submit the public key to the server, markup such as the following can be used:

<form action="processkey.cgi" method="post" enctype="multipart/form-data">
 <p><keygen name="key"></p>
 <p><input type=submit value="Submit key..."></p>
</form>

The server will then receive a form submission with a packaged RSA public key as the value of "key". This can then be used for various purposes, such as generating a client certificate, as mentioned above.

4.10.15 The output element

Categories
Flow content.
Phrasing content.
Listed, labelable, and resettable form-associated element.
Contexts in which this element can be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
for
form
name
DOM interface:
interface HTMLOutputElement : HTMLElement {
  [PutForwards=value] readonly attribute DOMSettableTokenList htmlFor;
  readonly attribute HTMLFormElement form;
           attribute DOMString name;

  readonly attribute DOMString type;
           attribute DOMString defaultValue;
           attribute DOMString value;

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);

  readonly attribute NodeList labels;
};

The output element represents the result of a calculation.

The for content attribute allows an explicit relationship to be made between the result of a calculation and the elements that represent the values that went into the calculation or that otherwise influenced the calculation. The for attribute, if specified, must contain a string consisting of an unordered set of unique space-separated tokens that are case-sensitive, each of which must have the value of an ID of an element in the same Document.

The form attribute is used to explicitly associate the output element with its form owner. The name attribute represents the element's name.

The element has a value mode flag which is either value or default. Initially, the value mode flag must be set to default.

The element also has a default value. Initially, the default value must be the empty string.

When the value mode flag is in mode default, the contents of the element represent both the value of the element and its default value. When the value mode flag is in mode value, the contents of the element represent the value of the element only, and the default value is only accessible using the defaultValue IDL attribute.

Whenever the element's descendants are changed in any way, if the value mode flag is in mode default, the element's default value must be set to the value of the element's textContent IDL attribute.

The reset algorithm for output elements is to set the element's value mode flag to default and then to set the element's textContent IDL attribute to the value of the element's default value (thus replacing the element's child nodes).

output . value [ = value ]

Returns the element's current value.

Can be set, to change the value.

output . defaultValue [ = value ]

Returns the element's current default value.

Can be set, to change the default value.

output . type

Returns the string "output".

The value IDL attribute must act like the element's textContent IDL attribute, except that on setting, in addition, before the child nodes are changed, the element's value mode flag must be set to value.

The defaultValue IDL attribute, on getting, must return the element's default value. On setting, the attribute must set the element's default value, and, if the element's value mode flag is in the mode default, set the element's textContent IDL attribute as well.

The type attribute must return the string "output".

The htmlFor IDL attribute must reflect the for content attribute.

The willValidate, validity, and validationMessage attributes, and the checkValidity() and setCustomValidity() methods, are part of the constraint validation API. The labels attribute provides a list of the element's labels. The form and name IDL attributes are part of the element's forms API.

Constraint validation: output elements are always barred from constraint validation.

A simple calculator could use output for its display of calculated results:

<form onsubmit="return false">
 <input name=a type=number step=any> +
 <input name=b type=number step=any> =
 <output onforminput="value = a.valueAsNumber + b.valueAsNumber"></output>
</form>

4.10.16 The progress element

ISSUE-96 (progress) blocks progress to Last Call

Categories
Flow content.
Phrasing content.
Labelable form-associated element.
Contexts in which this element can be used:
Where phrasing content is expected.
Content model:
Phrasing content, but there must be no progress element descendants.
Content attributes:
Global attributes
value
max
form
DOM interface:
interface HTMLProgressElement : HTMLElement {
           attribute double value;
           attribute double max;
  readonly attribute double position;
  readonly attribute HTMLFormElement form;
  readonly attribute NodeList labels;
};

The progress element represents the completion progress of a task. The progress is either indeterminate, indicating that progress is being made but that it is not clear how much more work remains to be done before the task is complete (e.g. because the task is waiting for a remote host to respond), or the progress is a number in the range zero to a maximum, giving the fraction of work that has so far been completed.

There are two attributes that determine the current task completion represented by the element. The value attribute specifies how much of the task has been completed, and the max attribute specifies how much work the task requires in total. The units are arbitrary and not specified.

Authors are encouraged to also include the current value and the maximum value inline as text inside the element, so that the progress is made available to users of legacy user agents.

Here is a snippet of a Web application that shows the progress of some automated task:

<section>
 <h2>Task Progress</h2>
 <p>Progress: <progress id="p" max=100><span>0</span>%</progress></p>
 <script>
  var progressBar = document.getElementById('p');
  function updateProgress(newValue) {
    progressBar.value = newValue;
    progressBar.getElementsByTagName('span')[0].textContent = newValue;
  }
 </script>
</section>

(The updateProgress() method in this example would be called by some other code on the page to update the actual progress bar as the task progressed.)

The value and max attributes, when present, must have values that are valid floating point numbers. The value attribute, if present, must have a value equal to or greater than zero, and less than or equal to the value of the max attribute, if present, or 1.0, otherwise. The max attribute, if present, must have a value greater than zero.

The progress element is the wrong element to use for something that is just a gauge, as opposed to task progress. For instance, indicating disk space usage using progress would be inappropriate. Instead, the meter element is available for such use cases.

User agent requirements: If the value attribute is omitted, then the progress bar is an indeterminate progress bar. Otherwise, it is a determinate progress bar.

If the progress bar is a determinate progress bar and the element has a max attribute, the user agent must parse the max attribute's value according to the rules for parsing floating point number values. If this does not result in an error, and if the parsed value is greater than zero, then the maximum value of the progress bar is that value. Otherwise, if the element has no max attribute, or if it has one but parsing it resulted in an error, or if the parsed value was less than or equal to zero, then the maximum value of the progress bar is 1.0.

If the progress bar is a determinate progress bar, user agents must parse the value attribute's value according to the rules for parsing floating point number values. If this does not result in an error, and if the parsed value is less than the maximum value and greater than zero, then the current value of the progress bar is that parsed value. Otherwise, if the parsed value was greater than or equal to the maximum value, then the current value of the progress bar is the maximum value of the progress bar. Otherwise, if parsing the value attribute's value resulted in an error, or a number less than or equal to zero, then the current value of the progress bar is zero.

UA requirements for showing the progress bar: When representing a progress element to the user, the UA should indicate whether it is a determinate or indeterminate progress bar, and in the former case, should indicate the relative position of the current value relative to the maximum value.

The form attribute is used to explicitly associate the progress element with its form owner.

progress . position

For a determinate progress bar (one with known current and maximum values), returns the result of dividing the current value by the maximum value.

For an indeterminate progress bar, returns −1.

If the progress bar is an indeterminate progress bar, then the position IDL attribute must return −1. Otherwise, it must return the result of dividing the current value by the maximum value.

Similarly, if the progress bar is an indeterminate progress bar, then the value IDL attribute, on getting, must return −1. Otherwise, it must return the current value. On setting, the given value must be converted to the best representation of the number as a floating point number and then the value content attribute must be set to that string.

The max IDL attribute must reflect the content attribute of the same name. The default value for max is 1.0.

The labels attribute provides a list of the element's labels. The form IDL attribute is part of the element's forms API.

4.10.17 The meter element

ISSUE-97 (meter) blocks progress to Last Call

Categories
Flow content.
Phrasing content.
Labelable form-associated element.
Contexts in which this element can be used:
Where phrasing content is expected.
Content model:
Phrasing content, but there must be no meter element descendants.
Content attributes:
Global attributes
value
min
max
low
high
optimum
form
DOM interface:
interface HTMLMeterElement : HTMLElement {
           attribute double value;
           attribute double min;
           attribute double max;
           attribute double low;
           attribute double high;
           attribute double optimum;
  readonly attribute HTMLFormElement form;
  readonly attribute NodeList labels;
};

The meter element represents a scalar measurement within a known range, or a fractional value; for example disk usage, the relevance of a query result, or the fraction of a voting population to have selected a particular candidate.

This is also known as a gauge.

The meter element should not be used to indicate progress (as in a progress bar). For that role, HTML provides a separate progress element.

The meter element also does not represent a scalar value of arbitrary range — for example, it would be wrong to use this to report a weight, or height, unless there is a known maximum value.

There are six attributes that determine the semantics of the gauge represented by the element.

The min attribute specifies the lower bound of the range, and the max attribute specifies the upper bound. The value attribute specifies the value to have the gauge indicate as the "measured" value.

The other three attributes can be used to segment the gauge's range into "low", "medium", and "high" parts, and to indicate which part of the gauge is the "optimum" part. The low attribute specifies the range that is considered to be the "low" part, and the high attribute specifies the range that is considered to be the "high" part. The optimum attribute gives the position that is "optimum"; if that is higher than the "high" value then this indicates that the higher the value, the better; if it's lower than the "low" mark then it indicates that lower values are better, and naturally if it is in between then it indicates that neither high nor low values are good.

Authoring requirements: The value attribute must be specified. The value, min, low, high, max, and optimum attributes, when present, must have values that are valid floating point numbers.

In addition, the attributes' values are further constrained:

Let value be the value attribute's number.

If the min attribute attribute is specified, then let minimum be that attribute's value; otherwise, let it be zero.

If the max attribute attribute is specified, then let maximum be that attribute's value; otherwise, let it be 1.0.

The following inequalities must hold, as applicable:

If no minimum or maximum is specified, then the range is assumed to be 0..1, and the value thus has to be within that range.

Authors are encouraged to include a textual representation of the gauge's state in the element's contents, for users of user agents that do not support the meter element.

The following examples show three gauges that would all be three-quarters full:

Storage space usage: <meter value=6 max=8>6 blocks used (out of 8 total)</meter>
Voter turnout: <meter value=0.75><img alt="75%" src="graph75.png"></meter>
Tickets sold: <meter min="0" max="100" value="75"></meter>

The following example is incorrect use of the element, because it doesn't give a range (and since the default maximum is 1, both of the gauges would end up looking maxed out):

<p>The grapefruit pie had a radius of <meter value=12>12cm</meter>
and a height of <meter value=2>2cm</meter>.</p> <!-- BAD! -->

Instead, one would either not include the meter element, or use the meter element with a defined range to give the dimensions in context compared to other pies:

<p>The grapefruit pie had a radius of 12cm and a height of
2cm.</p>
<dl>
 <dt>Radius: <dd> <meter min=0 max=20 value=12>12cm</meter>
 <dt>Height: <dd> <meter min=0 max=10 value=2>2cm</meter>
</dl>

There is no explicit way to specify units in the meter element, but the units may be specified in the title attribute in free-form text.

The example above could be extended to mention the units:

<dl>
 <dt>Radius: <dd> <meter min=0 max=20 value=12 title="centimeters">12cm</meter>
 <dt>Height: <dd> <meter min=0 max=10 value=2 title="centimeters">2cm</meter>
</dl>

User agent requirements: User agents must parse the min, max, value, low, high, and optimum attributes using the rules for parsing floating point number values.

User agents must then use all these numbers to obtain values for six points on the gauge, as follows. (The order in which these are evaluated is important, as some of the values refer to earlier ones.)

The minimum value

If the min attribute is specified and a value could be parsed out of it, then the minimum value is that value. Otherwise, the minimum value is zero.

The maximum value

If the max attribute is specified and a value could be parsed out of it, the maximum value is that value. Otherwise, the maximum value is 1.0.

If the maximum value would be less than the minimum value, then the maximum value is actually the same as the minimum value.

The actual value

If the value attribute is specified and a value could be parsed out of it, then that value is the actual value. Otherwise, the actual value is zero.

If the actual value would be less than the minimum value, then the actual value is actually the same as the minimum value.

If, on the other hand, the actual value would be greater than the maximum value, then the actual value is the maximum value.

The low boundary

If the low attribute is specified and a value could be parsed out of it, then the low boundary is that value. Otherwise, the low boundary is the same as the minimum value.

If the low boundary is then less than the minimum value, then the low boundary is actually the same as the minimum value. Similarly, if the low boundary is greater than the maximum value, then it is actually the maximum value instead.

The high boundary

If the high attribute is specified and a value could be parsed out of it, then the high boundary is that value. Otherwise, the high boundary is the same as the maximum value.

If the high boundary is then less than the low boundary, then the high boundary is actually the same as the low boundary. Similarly, if the high boundary is greater than the maximum value, then it is actually the maximum value instead.

The optimum point

If the optimum attribute is specified and a value could be parsed out of it, then the optimum point is that value. Otherwise, the optimum point is the midpoint between the minimum value and the maximum value.

If the optimum point is then less than the minimum value, then the optimum point is actually the same as the minimum value. Similarly, if the optimum point is greater than the maximum value, then it is actually the maximum value instead.

All of which will result in the following inequalities all being true:

UA requirements for regions of the gauge: If the optimum point is equal to the low boundary or the high boundary, or anywhere in between them, then the region between the low and high boundaries of the gauge must be treated as the optimum region, and the low and high parts, if any, must be treated as suboptimal. Otherwise, if the optimum point is less than the low boundary, then the region between the minimum value and the low boundary must be treated as the optimum region, the region between the low boundary and the high boundary must be treated as a suboptimal region, and the region between the high boundary and the maximum value must be treated as an even less good region. Finally, if the optimum point is higher than the high boundary, then the situation is reversed; the region between the high boundary and the maximum value must be treated as the optimum region, the region between the high boundary and the low boundary must be treated as a suboptimal region, and the remaining region between the low boundary and the minimum value must be treated as an even less good region.

UA requirements for showing the gauge: When representing a meter element to the user, the UA should indicate the relative position of the actual value to the minimum and maximum values, and the relationship between the actual value and the three regions of the gauge.

The following markup:

<h3>Suggested groups</h3>
<menu type="toolbar">
 <a href="?cmd=hsg" onclick="hideSuggestedGroups()">Hide suggested groups</a>
</menu>
<ul>
 <li>
  <p><a href="/group/comp.infosystems.www.authoring.stylesheets/view">comp.infosystems.www.authoring.stylesheets</a> -
     <a href="/group/comp.infosystems.www.authoring.stylesheets/subscribe">join</a></p>
  <p>Group description: <strong>Layout/presentation on the WWW.</strong></p>
  <p><meter value="0.5">Moderate activity,</meter> Usenet, 618 subscribers</p>
 </li>
 <li>
  <p><a href="/group/netscape.public.mozilla.xpinstall/view">netscape.public.mozilla.xpinstall</a> -
     <a href="/group/netscape.public.mozilla.xpinstall/subscribe">join</a></p>
  <p>Group description: <strong>Mozilla XPInstall discussion.</strong></p>
  <p><meter value="0.25">Low activity,</meter> Usenet, 22 subscribers</p>
 </li>
 <li>
  <p><a href="/group/mozilla.dev.general/view">mozilla.dev.general</a> -
     <a href="/group/mozilla.dev.general/subscribe">join</a></p>
  <p><meter value="0.25">Low activity,</meter> Usenet, 66 subscribers</p>
 </li>
</ul>

Might be rendered as follows:

With the <meter> elements rendered as inline green bars of varying lengths.

User agents may combine the value of the title attribute and the other attributes to provide context-sensitive help or inline text detailing the actual values.

For example, the following snippet:

<meter min=0 max=60 value=23.2 title=seconds></meter>

...might cause the user agent to display a gauge with a tooltip saying "Value: 23.2 out of 60." on one line and "seconds" on a second line.

The form attribute is used to explicitly associate the meter element with its form owner.

The value IDL attribute, on getting, must return the actual value. On setting, the given value must be converted to the best representation of the number as a floating point number and then the value content attribute must be set to that string.

The min, max, low, high, and optimum IDL attributes must reflect the respective content attributes of the same name.

The labels attribute provides a list of the element's labels. The form IDL attribute is part of the element's forms API.

The following example shows how a gauge could fall back to localized or pretty-printed text.

<p>Disk usage: <meter min=0 value=170261928 max=233257824>170 261 928 bytes used
out of 233 257 824 bytes available</meter></p>