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launch a web worker that can require() in the browser with browserify


First, a main.js file will launch the worker.js and print its output:

var work = require('webworkify');
var w = work(require('./worker.js'));
w.addEventListener('message', function (ev) {
w.postMessage(4); // send the worker a message

then worker.js can require() modules of its own. The worker function lives inside of the module.exports:

var gamma = require('gamma');
module.exports = function (self) {
    self.addEventListener('message',function (ev){
        var startNum = parseInt(; // from main.js
        setInterval(function () {
            var r = startNum / Math.random() - 1;
            self.postMessage([ startNum, r, gamma(r) ]);
        }, 500);

Now after browserifying this example, the console will contain output from the worker:

[ 4, 0.09162078520553618, 10.421030346237066 ]
[ 4, 2.026562457360466, 1.011522336481017 ]
[ 4, 3.1853125018703716, 2.3887589540750214 ]
[ 4, 5.6989969260510005, 72.40768854476167 ]
[ 4, 8.679491643020487, 20427.19357947782 ]
[ 4, 0.8528139834191428, 1.1098187157762498 ]
[ 4, 8.068322137547542, 5785.928308309402 ]


var work = require('webworkify')

var w = work(require(modulePath))

Return a new web worker from the module at modulePath.

The file at modulePath should export its worker code in module.exports as a function that will be run with no arguments.

Note that all the code outside of the module.exports function will be run in the main thread too so don't put any computationally intensive code in that part. It is necessary for the main code to require() the worker code to fetch the module reference and load modulePath's dependency graph into the bundle output.


The worker w returned by webworkify has the property objectURL attached. w.objectURL refers to the Object URL that was used to pass the module's source to the worker, and can be cleaned up using URL.revokeObjectURL(). (See example)


With npm do:

npm install webworkify