This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The MediaKeySession.expiration read-only property returns the time after which the keys in the current session can no longer be used to decrypt media data, or NaN if no such time exists. This value is determined by the CDM and measured in milliseconds since January 1, 1970, UTC. This value may change during a session lifetime, such as when an action triggers the start of a window.


​var expirationTime = mediaKeySessionObj.expiration;


Specification Status Comment
Encrypted Media Extensions
The definition of 'expiration' in that specification.
Recommendation Initial definition

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic support
Chrome Full support 42Edge Full support 13Firefox ? IE ? Opera Full support YesSafari ? WebView Android Full support 43Chrome Android Full support 42Edge Mobile Full support YesFirefox Android ? Opera Android Full support YesSafari iOS ? Samsung Internet Android Full support 4.0


Full support  
Full support
Compatibility unknown  
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.

Document Tags and Contributors

Contributors to this page: fscholz, libbymc, Sebastianz, meljag, jpmedley
Last updated by: fscholz,