Wait until ready w/javascript

jquery.onAvailable.js

$.fn.onAvailable = function(fn) {
  var sel = this.selector;
  var timer;
  if (this.length > 0) {
    fn.call(this);
  } else {
    timer = setInterval(function() {
      if ($(sel).length > 0) {
        fn.call($(sel));
        clearInterval(timer);
      }
    }, 100);
  }
};

onAvailable.js

(function(window, document) {

  /** Milliseconds between retries */
  var POLL_INTERVAL = 20;

  /** Number of attempts to locate element */
  var POLL_RETRIES = 2000;

  function onLoad(callback) {
    if (document.readyState === "complete") {
      setTimeout(callback, 1);
    } else if (document.addEventListener) {
      window.addEventListener("load", callback, false);
    } else {
      window.attachEvent("onload", callback);
    }
  }

  var isReady = false;
  onLoad(function() {
    isReady = true;
  });

  var interval = null,
    listeners = [],
    pollRetries;

  /**
   * Polls the DOM for an element matching the supplied id and fires the
   * associated callback method
   */
  function checkAvailable() {
    var i, l, listener, el, missed = 0;

    for (i = 0, l = listeners.length; i < l; i++) {
      listener = listeners[i];
      if (listener) {
        el = document.getElementById(listener.id);
        /**
         * If the DOM element is found, execute callbacks for all related
         * onAvailable listeners. If the DOM is ready or the next sibling
         * is detected, execute callbacks for all onContentReady listeners.
         */
        if (el && (!listener.checkContent || (listener.checkContent && (el.nextSibling || el.parentNode.nextSibling || isReady)))) {
          try {
            listener.callback.call(el, listener.obj);
          } catch (ex) {
            console.log(ex);
          }
          listeners[i] = null;
        } else {
          missed++;
        }
      }
    }

    pollRetries--;
    if (missed === 0 || pollRetries <= 0) {
      interval = window.clearInterval(interval);
      if (listeners.length) {
        listeners.splice(0, listeners.length);
      }
    }
    listener = el = null;
  }

  function onAvailable(id, callback, obj, checkContent) {
    pollRetries = POLL_RETRIES;
    listeners.push({
      id: id,
      callback: callback,
      obj: obj,
      checkContent: !! checkContent
    });
    if (!interval) {
      interval = window.setInterval(checkAvailable, POLL_INTERVAL);
    }
  }

  window.onAvailable = onAvailable;
}(window, document));

waitfor.js

(function() {
  if (typeof whatever !== 'undefined') {
    // do stuff with 'whatever'
  } else {
    // Keep checking until mmenu can launch
    setTimeout(arguments.callee, 50); //change this time
  }
})();