The action property is the only required property MediaSessionActionDetails dictionary, specifying the type of media session action which the action handler callback is being executed for. 
let mediaSessionActionDetails = { action: actionType }; let actionType = mediaSessionActionDetails.action;
 A DOMString specifying which of the action types the callback is being invoked for: 
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
action | 
73  | 
79  | 
 82 
71 
 | 
No  | 
No  | 
No  | 
No  | 
57  | 
 82 
Firefox exposes the API, but does not provide a corresponding user-facing media control interface. 
 | 
No  | 
No  | 
7.0  | 
MediaSession method setActionHandler() 
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    https://developer.mozilla.org/en-US/docs/Web/API/MediaSessionActionDetails/action