The active property of the ServiceWorkerRegistration interface returns a service worker whose ServiceWorker.state is activating or activated. This property is initially set to null.

An active worker controls a Client if the client's URL falls within the scope of the registration (the scope option set when ServiceWorkerContainer.register is first called.)

Note: This feature is available in Web Workers.

Note: Once an active worker is activating, neither a runtime script error nor a force termination of the active worker prevents the active worker from getting activated.


var serviceWorker =;


A ServiceWorker object's property, if it is currently in an activating or activated state.


Specification Status Comment
Service Workers
The definition of '' in that specification.
Working Draft Initial definition.

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See also