ready.js

var app = {}

!function (app) {
  // container to push booleans
  // for each event to indicate whether
  // the `app` is ready
  var isReady = [];

  // the ready stack to house
  // all of the callbacks pushed
  // to it
  var readyStack = [];

  app.ready = function (e, fn) {
    // ensure `event` is a string
    if ('string' !== typeof e) throw new TypeError("expecting string");

    // ensure `fn` is a function
    if ('function' !== typeof fn) throw new TypeError("expecting function");

    // `app` is already ready so
    // we can just call the `fn`
    // function
    if (isReady[isReady.indexOf(e)]) {
      // wait for next tick in event loop
      // to keep things asynchronous
      setTimeout(fn.bind(app), 0);
    } else {
      if ('array' !== typeof readyStack[e]) readyStack[e] = [];
      readyStack[e].push(fn.bind(app));
    }

    // chaining is classy
    return this;
  };

  app.emitReady = function (e) {
    if (!readyStack[e]) throw new TypeError("ready event '" + e + "' is undefined");

    var fn, i, len = readyStack[e].length

    // set internal `isReady` boolean
    // to true so the `app` knows
    // it is ready
    isReady[e] = true;

    // iterate and call each callback
    // in the `readyStack`
    for (i = 0; i < len; ++i) {
      fn = readyStack[e][i];
      // execute the callback
      fn();
    }
  }

}(app);