How does #onmessage and #postmessage work to communicate between main thread and HTML5's webworkers?

Question

I\"m learning about HTML5 workers from here and the author uses self.onmessage and self.postmessage to communicate between the main thread and the work

Answer 1

in your file worker.js think of the self.postMessage as the order/instruction that the worker (self) should post a message. Since it is only able to communicate with the mainJS which created it, this message goes there. :) Also in your mainJS worker.onmessage should be understood as the event "a message comes from the worker".

So basically you have both options in both your scripts: in mainJS: worker.postMessage("message"); to send a message to the worker - and worker.onmessage = function(event){...} to listen to messages from the worker

in worker script: (self or) this.onmessage = function(event){...} to listen to messages from the mainJS - and self.postMessage("message"); to send something back to mainJS