requirejs-worker-spawn

spawn.js

define(function(require) {
   'use strict';

    const REQUIRE_URL = getRequireJsUrl();
    const BASE_URL = getRequireJSBaseUrl();

    function spawn(data, fn) {
        return new Promise(function(res, rej) {
            let wrapper = buildWrapper(fn);
            let url = functionToUrl(wrapper);
            let worker = new Worker(url);
            worker.onmessage = res;
            worker.onerror = rej;
            URL.revokeObjectURL(url);
        });
    }

    function buildWrapper(fn) {
        let wrapper = `(function() {
        'use strict';
        importScripts('${REQUIRE_URL}');
        require.config({ baseUrl : '${BASE_URL}' });
        let _init = ${fn.toString()};
        let _onComplete = function(result) {
         self.postMessage(result); self.close(); }
        _init(null, require, _onComplete);
        })()`;
        return wrapper;
    }

    function getRequireJsUrl() {
        let filename = 'require.js';
        let scripts = document.getElementsByTagName('script');
        let src;
        for(let i = 0, len = scripts.length; i < len; i++) {
            src = scripts[i].src;
            if(src.indexOf(filename) > -1) {
                let parts = src.split('/');
                if(parts[parts.length-1] === filename) {
                    return src;
                }
            }
        }
        return null;
    }

    function getRequireJSBaseUrl() {
        let requireBaseUrl = require.toUrl('');
        let href = window.location.href;
        let endIdx = href.lastIndexOf('/');
        let result = href.substring(0, endIdx) + '/' + requireBaseUrl;
        return result;
    }

    function functionToUrl(fnString) {
        let blob = new Blob([ fnString ],
            { type: 'application/javascript' } );
        let url = URL.createObjectURL(blob);
        return url;
    }

    spawn(null, function(data, require, onComplete) {
        require(['core/someModule'], function(mod) {
            onComplete('my results');
        });
    }).then(function(res) {
        console.log(res);
    });
});