Asynchronous JavaScript Loader

include.js

// Async Loader v1.0.0
var include = function(scripts, done) {
  if (typeof scripts === 'string') scripts = [scripts];
  var loading = function() { scripts.pop() && !scripts.length && done && done.call(); };
  scripts.forEach(function (script) {
    var el = document.createElement('script');
    el.addEventListener('load', loading), el.async = true, el.src = script;
    document.head.appendChild(el);
  });
  return arguments.callee;
};