HTMLTrackElement - Web APIs 编辑

The HTMLTrackElement interface represents an HTML <track> element within the DOM. This element can be used as a child of either <audio> or <video> to specify a text track containing information such as closed captions or subtitles.

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Properties

Inherits properties from its parent, HTMLElement.

HTMLTrackElement.kind

Is a DOMString that reflects the kind HTML attribute, indicating how the text track is meant to be used. Possible values are: subtitles, captions, descriptions, chapters, or metadata.

HTMLTrackElement.src

Is a DOMString that reflects the src HTML attribute, indicating the address of the text track data.

HTMLTrackElement.srclang

Is a DOMString that reflects the srclang HTML attribute, indicating the language of the text track data.

HTMLTrackElement.label

Is a DOMString that reflects the label HTML attribute, indicating a user-readable title for the track.

HTMLTrackElement.default

A Boolean reflecting the default  attribute, indicating that the track is to be enabled if the user's preferences do not indicate that another track would be more appropriate.

HTMLTrackElement.readyState Read only

Returns  an unsigned short that show the readiness state of the track:

Constant	Value	Description
NONE	0	Indicates that the text track's cues have not been obtained.
LOADING	1	Indicates that the text track is loading and there have been no fatal errors encountered so far. Further cues might still be added to the track by the parser.
LOADED	2	Indicates that the text track has been loaded with no fatal errors.
ERROR	3	Indicates that the text track was enabled, but when the user agent attempted to obtain it, this failed in some way. Some or all of the cues are likely missing and will not be obtained.

HTMLTrackElement.track Read only

Returns TextTrack is the track element's text track data.

Methods

No specific method; inherits methods from its parent, HTMLElement.

Events

The following events may be fired on a <track> element, in addition to any that may be fired at its parent, HTMLElement.

cuechange

Sent when the underlying TextTrack has changed the currently-presented cues. This event is always sent to the TextTrack but is also sent to the HTMLTrackElement if one is associated with the track.
You may also use the oncuechange event handler to establish a handler for this event.

Usage notes

Loading of the track's text resource

The WebVTT or TTML data describing the actual cues for the text track isn't loaded if the track's mode is initially in the disabled state. If you need to be able to perform any processing on the track after the <track> is set up, you should instead ensure that the track's mode is either hidden (if you don't want it to start out being presented to the user) or showing (to initially display the track). You can then change the mode as desired later.

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• The HTML element implementing this interface: <track>.