How to pass functions to JavaScript Web Worker

Question

I would like to pass a function (or functions) via a postMessage() to a web worker, because I can't refer to regular files.

To kick the web worker off, I am passing an object URL (created from a Blob) to the Worker constructor. Then I am passing a message, but so far no luck putting a function in the message.

The (JSON) message cannot contain functions directly (as stipulated here), and although importScripts is theoretically allowed, I have not had any success using it so far in Chrome or Firefox.

The body of the html file:

<div id="divText">1234</div> <script>     var greeter = function greet(name) {         return "hello " + name;     };     function webWorkerWorker() {         self.postMessage("started1");         self.onmessage = function(event) {             importScripts(event.data.content);             self.postMessage("importScripts success");             var result = greeter("john");             self.postMessage(result);         };     }     var functionBody = mylib.extractFunctionBody(webWorkerWorker);     var functionBlob = mylib.createBlob([functionBody]);     var functionUrl = mylib.createObjectURL(functionBlob);      var functionBody2 = mylib.extractFunctionBody(greeter);     var functionBlob2 = mylib.createBlob([greeter]);     var functionUrl2 = mylib.createObjectURL(functionBlob2);      var worker = new Worker(functionUrl);     worker.onmessage = function(event) {         document.getElementById("divText").innerHTML = event.data;     }     worker.postMessage({                 type: "init",                 content: functionUrl2             }); </script> 

Currently it results in setting the divText value to "importScripts success".

Am I doing something wrong? Is there another way that functions can be passed to web workers? Or is it not possible?

Answer 1

Turns out this method works fine, there was merely a bug in my worker:

var result = greeter("john"); 

should be

var result = greet("john"); 

which makes sense - I'm passing the greeter variable to the worker, but there's no reason for it to know the variable name of the object I'm passing.