loader.js

(function (root, factory) {
  if (typeof define === 'function' && define.amd) {
    // AMD
    define([], factory);
  } else if (typeof exports === 'object') {
    // Node, CommonJS-like
    module.exports = factory();
  } else {
    // Browser globals (root is window)
    root.loader = factory();
  }
}(this, function () {
  return function loadModule(moduleUrl, path, callback) {
    return new Promise(function(resolve, reject) {
      var solverObj = null;

      var request = new XMLHttpRequest();
      request.onreadystatechange = function () {
        var DONE = request.DONE || 4;
        if (request.readyState === DONE){
          if (request.status == 200) {
            // emscripten puts Module into global namespace if it
            // determines that it runs in the web
            // save potential old window.Module
            var oldWindowModule;
            if (window.Module) {
              oldWindowModule = window.Module;
            }

            console.log("Evaluating asmjs code...");
            var newCode = "var memoryInitializerPath = '" + path + "';" + request.responseText;
            solverObj = new Function(newCode)();

            if (oldWindowModule) {
              window.Module = oldWindowModule;
            } else {
              delete window.Module;
            }
            resolve(solverObj);
          } else {
            console.error("Error while loading ", moduleUrl);
          }
        }
      };
      request.open("GET", path + moduleUrl);
      request.send();
    });
  };
}));