This feature is not Baseline because it does not work in some of the most widely-used browsers.
The positionAlign property of the VTTCue interface is used to determine what VTTCue.position is anchored to.
A string containing one of the following values:
"line-left"Line-left alignment.
"center"Center alignment.
"line-right"Line-right alignment.
"auto"Automatic alignment, which depends on the text alignment of the cue, interpreted as follows:
In the following example a new VTTCue is created, then the value of positionAlign is set to "line-right". The value is then printed to the console.
let video = document.querySelector("video");
let track = video.addTextTrack("captions", "Captions", "en");
track.mode = "showing";
let cue = new VTTCue(0, 0.9, "Hildy!");
cue.positionAlign = "line-right";
console.log(cue.positionAlign);
track.addCue(cue);
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Opera | Safari | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | WebView Android | WebView on iOS | |
positionAlign |
No | No | 31 | No | 14.1 | No | 31 | No | 14.5 | No | No | 14.5 |
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https://developer.mozilla.org/en-US/docs/Web/API/VTTCue/positionAlign