A quick implementation of AMD

amd.js

(function () {
  
  var filename = "amd.js";

  var scripts = Array.prototype.slice.call(document.querySelectorAll("script[src]"));
  var self = scripts.filter(function (x) { return x.getAttribute("src").indexOf(filename) > -1; })[0];
  var src = self.getAttribute("src");
  var root = src.substring(0, src.indexOf(filename));

  var modules = {};

  this.define = function (def) {
    var src = document.currentScript.getAttribute("src");
    modules[src] = def;
  };

  function loading(state, done) {
    state.count--;
    if (state.count == 0) done();
  }

  this.require = function (sources, callback) {
    function done() {
      var m = sources.map(function (x) { return modules[root + x + ".js"](); });
      callback.apply(this, m);
    }
    var unloaded = sources.filter(function (x) {
      return !(x in modules);
    });
    var state = { count: unloaded.length };
    unloaded.forEach(function (x) {
      var script = document.createElement("script");
      script.onload = loading.bind(script, state, done);
      script.src = root + x + ".js";
      document.head.appendChild(script);
    });
    if (state.count == 0) done();
  };

}).call(this);