Turn a function's body into a worker.

workerify.js

// Turns a function's body into a worker
var workerify = function (func) {
    if (typeof func !== 'function') {
        throw new Error('expects a function to workerify.')
    }
    var script = func.toString().match(/^function[^{]*{((.|\n)*)}$/)[1],
        blob   = new Blob([script], {'type': 'application/javascript'}),
        url    = window.URL.createObjectURL(blob)
    return new Worker(url)
}

// Usage Example:
var worker = workerify(function () {
    // just write code as if you are inside a worker
    // note: you don't have access to anything outside of this function
    self.onmessage = function (e) {
        self.postMessage('pong')
    }
})

worker.onmessage = function (e) {
    console.log(e.data)
}

worker.postMessage('ping') // pong

This also comes handy when trying to pack a worker script into a Browserify bundle:

// main.js
var worker = workerify(require('./worker-script'))

// worker-script.js
module.exports = function () {
    // do work
}