This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The readyState read-only property of the HTMLTrackElement interface returns a number representing the <track> element's text track readiness state:
A number; 0, 1, 2, or 3.
const trackElement = document.getElementById("exampleTrack");
console.log(trackElement.readyState); // 0, 1, 2, or 3
| Specification |
|---|
| HTML> # dom-track-readystate-dev> |
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Opera | Safari | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | WebView Android | WebView on iOS | |
readyState |
23 | 12 | 31 | 12 | 6 | 25 | 31 | 12 | 6 | 1.5 | 4.4 | 6 |
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https://developer.mozilla.org/en-US/docs/Web/API/HTMLTrackElement/readyState