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:

• line-left: if the text alignment is left, the cue is using a LTR language and the text alignment is start, or the cue is using a RTL language and the text alignment is end.
• line-right: if the text alignment is right, the cue is using a RTL language and the text alignment is start, or the cue is using a LTR language and the text-alignment is end.
• center: if there is no text alignment position set.

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 cue1 = new VTTCue(0, 0.9, "Hildy!");
cue1.positionAlign = "line-right";
console.log(cue1.positionAlign);

track.addCue(cue1);