The onenter EventHandler of the TextTrackCue interface processes the enter event.
The enter event fires when a cue becomes active. In the case of subtitles or a caption this is when it displays over the media.
TextTrackCue.onenter = function; TextTrackCue.addEventListener('enter', function);
In the following example, onenter is used to print to the console when cue1 is the active cue.
cue1.onenter = function() { console.log('Cue 1 has displayed'); }
| Specification | 
|---|
| HTML Standard (HTML) # handler-texttrackcue-onenter  | 
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
onenter | 
23  | 
12  | 
31  | 
10  | 
≤12.1  | 
6  | 
≤37  | 
25  | 
31  | 
≤12.1  | 
7  | 
1.5  | 
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    https://developer.mozilla.org/en-US/docs/Web/API/TextTrackCue/onenter