message (Web Workers)

Bubbles	No
Cancelable	No
Target objects	ServiceWorkerContainer, or ServiceWorkerGlobalScope, depending on context.
Interface	ServiceWorkerMessageEvent or ExtendableMessageEvent, depending on context.

Examples

When the following code is used inside the main thread to set up a message channel between it and a service worker for sending messages between the two, the event object of onmessage will be a ServiceWorkerMessageEvent.

navigator.serviceWorker.ready.then(function(reg) {  

  ...

      // set up a message channel to communicate with the SW
      var channel = new MessageChannel();
      channel.port1.onmessage = function(e) {
        console.log(e);
        handleChannelMessage(e.data);
      }
      
      mySW = reg.active;
      mySW.postMessage('hello', [channel.port2]);
  });

Inheritance

When fired on a ServiceWorkerContainer object, the message event implements the ServiceworkerMessageEvent interface, which inherits from the Event interface — it therefore has available the properties and methods defined on both interfaces.

When fired on a ServiceWorkerGlobalScope object, the message event implements the ExtendableMessageEvent interface, which inherits from the ExtendableEvent interface — it therefore has available the properties and methods defined on both interfaces.

Specifications

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

Browser compatibility

See also

• Using Service Workers
• Service workers basic code example
• Is ServiceWorker ready?
• Using web workers