MediaSessionActionDetails

The Media Session API's MediaSessionActionDetails dictionary is the type used by the sole input parameter into the callback which is executed when a media session action occurs. It specifies the type of action which needs to be performed as well as the data needed to perform the action.

Properties

action

A Media Session action type string taken from the MediaSessionAction enumerated type, indicating which type of action needs to be performed. See Media action types below for possible values.

fastSeek Optional

An seekto action may optionally include this property, which is a Boolean value indicating whether or not to perform a "fast" seek. A "fast" seek is a seek being performed in a rapid sequence, such as when fast-forwarding or reversing through the media, rapidly skipping through it. This property can be used to indicate that you should use the shortest possible method to seek the media. fastSeek is not included on the final action in the seek sequence in this situation.

seekOffset Optional

If the action is either seekforward or seekbackward and this property is present, it is a floating point value which indicates the number of seconds to move the play position forward or backward. If this property isn't present, those actions should choose a reasonable default distance to skip forward or backward (such as 7 or 10 seconds).

seekTime Optional

If the action is seekto, this property must be present and must be a floating-point value indicating the absolute time within the media to move the playback position to, where 0 indicates the beginning of the media. This property is not present for other action types.

Media action types

A media session action's type is specified using a string from the MediaSessionAction enumerated type.

Values

Each of the actions is a common media session control request. Implement support for each of these in order to allow that type of action to be performed. The following strings identify the currently available types of media session action:

let skipTime = 10; // Time to skip in seconds

navigator.mediaSession.setActionHandler('seekforward', evt => {
 // User clicked "Seek Forward" media notification icon.
 audio.currentTime = Math.min(audio.currentTime + skipTime,  
               audio.duration);
});

navigator.mediaSession.setActionHandler('seekbackward', evt => {
 // User clicked "Seek Backward" media notification icon.
 audio.currentTime = Math.max(audio.currentTime - skipTime, 0);
});

let skipTime = 7;

navigator.mediaSession.setActionHandler("seekforward", handleSeek);
navigator.mediaSession.setActionHandler("seekbackward", handleSeek);

function handleSeek(details) {
  switch(details.action) {
    case "seekforward":
      audio.currentTime = Math.min(audio.currentTime + skipTime,
              audio.duration);
      break;
    case "seekbackward":
      audio.currentTime = Math.max(audio.currentTime - skipTime, 0);
      break;
  }
}

Examples

Adding action handlers

This example implements seek forward and backward actions for an audio player by setting up the seekforward and seekbackward action handlers.

let skipTime = 10; // Time to skip in seconds

navigator.mediaSession.setActionHandler('seekforward', details => {
 // User clicked "Seek Forward" media notification icon.
 audio.currentTime = Math.min(audio.currentTime + skipTime,  
               audio.duration);
});

navigator.mediaSession.setActionHandler('seekbackward', details => {
 // User clicked "Seek Backward" media notification icon.
 audio.currentTime = Math.max(audio.currentTime - skipTime, 0);
});

In this case, both the seekforward and seekbackward handlers are using a fixed distance, ignoring the time specified by the MediaSessionActionDetails passed into the handler.

Supporting multiple actions in one handler function

You can also, if you prefer, use a single function to handle multiple action types, by checking the value of the MediaSessionActionDetails object's action property:

let skipTime = 7;

navigator.mediaSession.setActionHandler("seekforward", handleSeek);
navigator.mediaSession.setActionHandler("seekbackward", handleSeek);

function handleSeek(details) {
  switch(details.action) {
    case "seekforward":
      audio.currentTime = Math.min(audio.currentTime + skipTime,
              audio.duration);
      break;
    case "seekbackward":
      audio.currentTime = Math.max(audio.currentTime - skipTime, 0);
      break;
  }
}

Here, the handleSeek() function handles both seekbackward and seekforward actions.

Using data provided by MediaSessionActionDetails

In this example, instead of seeking a specified distance, the seekforward and seekbackward handlers use the time specified in the MediaSessionActionDetails object's seekOffset property.

navigator.mediaSession.setActionHandler("seekforward", handleSeek);
navigator.mediaSession.setActionHandler("seekbackward", handleSeek);

function handleSeek(details) {
  switch(details.action) {
    case "seekforward":
      audio.currentTime = Math.min(audio.currentTime + details.seekOffset,
                                   audio.duration);
      break;
    case "seekbackward":
      audio.currentTime = Math.max(audio.currentTime - details.seekOffset, 0);
      break;
  }
});

Specifications

Browser compatibility