The Media Session API'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.



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.


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:


Advances playback to the next track.


Pauses playback of the media.


Begins (or resumes) playback of the media.


Moves back to the previous track.


Seeks backward through the media from the current position. The MediaSessionActionDetails property seekOffset specifies the amount of time to seek backward.


Seeks forward from the current position through the media. The MediaSessionActionDetails property seekOffset specifies the amount of time to seek forward.


Moves the playback position to the specified time within the media. The time to which to seek is specified in the MediaSessionActionDetails property seekTime. If you intend to perform multiple seekto operations in rapid succession, you can also specify the MediaSessionActionDetails property fastSeek property with a value of true. This lets the browser know it can take steps to optimize repeated operations, and is likely to result in improved performance.


Skips past the currently playing advertisement or commercial. This action may or may not be available, depending on the platform and user agent, or may be disabled due to subscription level or other circumstances.


Halts playback entirely.


See MediaSessionAction for example code.


Media Session Standard (Media Session)
# the-mediasessionactiondetails-dictionary

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