– Table of contents –
      1. 4.11.5 Commands
        1. 4.11.5.1 Using the a element to define a command
        2. 4.11.5.2 Using the button element to define a command
        3. 4.11.5.3 Using the input element to define a command
        4. 4.11.5.4 Using the option element to define a command
        5. 4.11.5.5 Using the command element to define a command
        6. 4.11.5.6 Using the accesskey attribute on a label element to define a command
        7. 4.11.5.7 Using the accesskey attribute on a legend element to define a command
        8. 4.11.5.8 Using the accesskey attribute to define a command on other elements

This is a work in progress! For the latest updates from the HTML WG, possibly including important bug fixes, please look at the editor's draft instead.

4.11.5 Commands

A command is the abstraction behind menu items, buttons, and links.

Commands are defined to have the following facets:

Type
The kind of command: "command", meaning it is a normal command; "radio", meaning that triggering the command will, amongst other things, set the Checked State to true (and probably uncheck some other commands); or "checkbox", meaning that triggering the command will, amongst other things, toggle the value of the Checked State.
ID
The name of the command, for referring to the command from the markup or from script. If a command has no ID, it is an anonymous command.
Label
The name of the command as seen by the user.
Hint
A helpful or descriptive string that can be shown to the user.
Icon
An absolute URL identifying a graphical image that represents the action. A command might not have an Icon.
Access Key
A key combination selected by the user agent that triggers the command. A command might not have an Access Key.
Hidden State
Whether the command is hidden or not (basically, whether it should be shown in menus).
Disabled State
Whether the command is relevant and can be triggered or not.
Checked State
Whether the command is checked or not.
Action
The actual effect that triggering the command will have. This could be a scripted event handler, a URL to which to navigate, or a form submission.

These facets are exposed on elements using the command API:

element . commandType

Exposes the Type facet of the command.

element . id

Exposes the ID facet of the command.

element . label

Exposes the Label facet of the command.

element . title

Exposes the Hint facet of the command.

element . icon

Exposes the Icon facet of the command.

element . accessKeyLabel

Exposes the Access Key facet of the command.

element . hidden

Exposes the state of the element's hidden attribute, which is generally equivalent to the Hidden State facet of the command. For label and legend elements (used in conjunction with the accesskey attribute), the Hidden State facet is derived from another element (the one that the assigned access key will trigger), and cannot be directly accessed from the element.

element . disabled

Exposes the Disabled State facet of the command.

element . checked

Exposes the Checked State facet of the command.

element . click()

Triggers the Action of the command.

The commandType attribute must return a string whose value is either "command", "radio", or "checkbox", depending on whether the Type of the command defined by the element is "command", "radio", or "checkbox" respectively. If the element does not define a command, it must return null.

The label attribute must return the command's Label, or null if the element does not define a command or does not specify a Label. This attribute will be shadowed by the label IDL attribute on various elements.

The icon attribute must return the absolute URL of the command's Icon. If the element does not specify an icon, or if the element does not define a command, then the attribute must return null. This attribute will be shadowed by the icon IDL attribute on command elements.

The disabled attribute must return true if the command's Disabled State is that the command is disabled, and false if the command is not disabled. This attribute is not affected by the command's Hidden State. If the element does not define a command, the attribute must return false. This attribute will be shadowed by the disabled IDL attribute on various elements.

The checked attribute must return true if the command's Checked State is that the command is checked, and false if it is that the command is not checked. If the element does not define a command, the attribute must return false. This attribute will be shadowed by the checked IDL attribute on input and command elements.

The ID facet is exposed by the id IDL attribute, the Hint facet is exposed by the title IDL attribute, the AccessKey facet is exposed by the accessKeyLabel IDL attribute, and the Hidden State facet is exposed by the hidden IDL attribute.

document . commands

Returns an HTMLCollection of the elements in the Document that define commands and have IDs.

The commands attribute of the document's HTMLDocument interface must return an HTMLCollection rooted at the Document node, whose filter matches only elements that define commands and have IDs.

User agents may expose the commands whose Hidden State facet is false (visible), e.g. in the user agent's menu bar. User agents are encouraged to do this especially for commands that have Access Keys, as a way to advertise those keys to the user.

4.11.5.1 Using the a element to define a command

An a element with an href attribute defines a command.

The Type of the command is "command".

The ID of the command is the value of the id attribute of the element, if the attribute is present and not empty. Otherwise the command is an anonymous command.

The Label of the command is the string given by the element's textContent IDL attribute.

The Hint of the command is the value of the title attribute of the element. If the attribute is not present, the Hint is the empty string.

The Icon of the command is the absolute URL obtained from resolving the value of the src attribute of the first img element descendant of the element, relative to that element, if there is such an element and resolving its attribute is successful. Otherwise, there is no Icon for the command.

The AccessKey of the command is the element's assigned access key, if any.

The Hidden State of the command is true (hidden) if the element has a hidden attribute, and false otherwise.

The Disabled State facet of the command is always false. (The command is always enabled.)

The Checked State of the command is always false. (The command is never checked.)

The Action of the command is to fire a click event at the element.

4.11.5.2 Using the button element to define a command

A button element always defines a command.

The Type, ID, Label, Hint, Icon, Access Key, Hidden State, Checked State, and Action facets of the command are determined as for a elements (see the previous section).

The Disabled State of the command mirrors the disabled state of the button.

4.11.5.3 Using the input element to define a command

An input element whose type attribute is in one of the Submit Button, Reset Button, Image Button, Button, Radio Button, or Checkbox states defines a command.

The Type of the command is "radio" if the type attribute is in the Radio Button state, "checkbox" if the type attribute is in the Checkbox state, and "command" otherwise.

The ID of the command is the value of the id attribute of the element, if the attribute is present and not empty. Otherwise the command is an anonymous command.

The Label of the command depends on the Type of the command:

If the Type is "command", then it is the string given by the value attribute, if any, and a UA-dependent, locale-dependent value that the UA uses to label the button itself if the attribute is absent.

Otherwise, the Type is "radio" or "checkbox". If the element is a labeled control, the textContent of the first label element in tree order whose labeled control is the element in question is the Label (in DOM terms, this is the string given by element.labels[0].textContent). Otherwise, the value of the value attribute, if present, is the Label. Otherwise, the Label is the empty string.

The Hint of the command is the value of the title attribute of the input element. If the attribute is not present, the Hint is the empty string.

If the element's type attribute is in the Image Button state, and the element has a src attribute, and that attribute's value can be successfully resolved relative to the element, then the Icon of the command is the absolute URL obtained from resolving that attribute that way. Otherwise, there is no Icon for the command.

The AccessKey of the command is the element's assigned access key, if any.

The Hidden State of the command is true (hidden) if the element has a hidden attribute, and false otherwise.

The Disabled State of the command mirrors the disabled state of the control.

The Checked State of the command is true if the command is of Type "radio" or "checkbox" and the element is checked attribute, and false otherwise.

The Action of the command, if the element has a defined activation behavior, is to run synthetic click activation steps on the element. Otherwise, it is just to fire a click event at the element.

4.11.5.4 Using the option element to define a command

An option element with an ancestor select element and either no value attribute or a value attribute that is not the empty string defines a command.

The Type of the command is "radio" if the option's nearest ancestor select element has no multiple attribute, and "checkbox" if it does.

The ID of the command is the value of the id attribute of the element, if the attribute is present and not empty. Otherwise the command is an anonymous command.

The Label of the command is the value of the option element's label attribute, if there is one, or the value of the option element's textContent IDL attribute if there isn't.

The Hint of the command is the string given by the element's title attribute, if any, and the empty string if the attribute is absent.

There is no Icon for the command.

The AccessKey of the command is the element's assigned access key, if any.

The Hidden State of the command is true (hidden) if the element has a hidden attribute, and false otherwise.

The Disabled State of the command is true (disabled) if the element is disabled or if its nearest ancestor select element is disabled, and false otherwise.

The Checked State of the command is true (checked) if the element's selectedness is true, and false otherwise.

The Action of the command depends on its Type. If the command is of Type "radio" then it must pick the option element. Otherwise, it must toggle the option element.

4.11.5.5 Using the command element to define a command

A command element defines a command.

The Type of the command is "radio" if the command's type attribute is "radio", "checkbox" if the attribute's value is "checkbox", and "command" otherwise.

The ID of the command is the value of the id attribute of the element, if the attribute is present and not empty. Otherwise the command is an anonymous command.

The Label of the command is the value of the element's label attribute, if there is one, or the empty string if it doesn't.

The Hint of the command is the string given by the element's title attribute, if any, and the empty string if the attribute is absent.

The Icon for the command is the absolute URL obtained from resolving the value of the element's icon attribute, relative to the element, if it has such an attribute and resolving it is successful. Otherwise, there is no Icon for the command.

The AccessKey of the command is the element's assigned access key, if any.

The Hidden State of the command is true (hidden) if the element has a hidden attribute, and false otherwise.

The Disabled State of the command is true (disabled) if the element has a disabled attribute, and false otherwise.

The Checked State of the command is true (checked) if the element has a checked attribute, and false otherwise.

The Action of the command, if the element has a defined activation behavior, is to run synthetic click activation steps on the element. Otherwise, it is just to fire a click event at the element.

4.11.5.6 Using the accesskey attribute on a label element to define a command

A label element that has an assigned access key and a labeled control and whose labeled control defines a command, itself defines a command.

The Type of the command is "command".

The ID of the command is the value of the id attribute of the element, if the attribute is present and not empty. Otherwise the command is an anonymous command.

The Label of the command is the string given by the element's textContent IDL attribute.

The Hint of the command is the value of the title attribute of the element.

There is no Icon for the command.

The AccessKey of the command is the element's assigned access key.

The Hidden State, Disabled State, and Action facets of the command are the same as the respective facets of the element's labeled control.

The Checked State of the command is always false. (The command is never checked.)

4.11.5.7 Using the accesskey attribute on a legend element to define a command

A legend element that has an assigned access key and is a child of a fieldset element that has a descendant that is not a descendant of the legend element and is neither a label element nor a legend element but that defines a command, itself defines a command.

The Type of the command is "command".

The ID of the command is the value of the id attribute of the element, if the attribute is present and not empty. Otherwise the command is an anonymous command.

The Label of the command is the string given by the element's textContent IDL attribute.

The Hint of the command is the value of the title attribute of the element.

There is no Icon for the command.

The AccessKey of the command is the element's assigned access key.

The Hidden State, Disabled State, and Action facets of the command are the same as the respective facets of the first element in tree order that is a descendant of the parent of the legend element that defines a command but is not a descendant of the legend element and is neither a label nor a legend element.

The Checked State of the command is always false. (The command is never checked.)

4.11.5.8 Using the accesskey attribute to define a command on other elements

An element that has an assigned access key defines a command.

If one of the other sections that define elements that define commands define that this element defines a command, then that section applies to this element, and this section does not. Otherwise, this section applies to that element.

The Type of the command is "command".

The ID of the command is the value of the id attribute of the element, if the attribute is present and not empty. Otherwise the command is an anonymous command.

The Label of the command depends on the element. If the element is a labeled control, the textContent of the first label element in tree order whose labeled control is the element in question is the Label (in DOM terms, this is the string given by element.labels[0].textContent). Otherwise, the Label is the textContent of the element itself.

The Hint of the command is the value of the title attribute of the element. If the attribute is not present, the Hint is the empty string.

There is no Icon for the command.

The AccessKey of the command is the element's assigned access key.

The Hidden State of the command is true (hidden) if the element has a hidden attribute, and false otherwise.

The Disabled State facet of the command is always false. (The command is always enabled.)

The Checked State of the command is always false. (The command is never checked.)

The Action of the command is to run the following steps:

  1. If the element is focusable, run the focusing steps for the element.
  2. If the element has a defined activation behavior, run synthetic click activation steps on the element.
  3. Otherwise, if the element does not have a defined activation behavior, fire a click event at the element.