waitUntil

waitUntil.js

 /**
  * @test - condition to check
  * @action - do something
  * @tryInterval - how often to try (default to 50ms)
  * @sharedTimer - if sharedTimer is specified, clear it when action is fired
  * @eachTime - function to run each time the condition is checked
  * returns timer
  */
  function waitUntil (test,action,tryInterval,sharedTimer,eachTime) {
     var timer = setInterval(function() {
        typeof eachTime === "function" && eachTime();
        if (test()) { 
            clearInterval(timer);
            sharedTimer && clearInterval(sharedTimer);
            action();
        }
    }, tryInterval || 50);

    return timer;
  }




  // Examples:

  // To test this, we'll start with g === 1 and then increment g slowly over a matter of seconds
  var g = 1;
  var timer2 = setInterval(function(){console.log("incrementing g..."); g++;},750);


  // Do something when g is === to an expected value
  var timer = waitUntil(ifGEquals7,doSomething,100,timer2);

  function ifGEquals7 () {
    return g === 7;
  }

  function doSomething () {
    console.log ("g === 7");
  }
​



  // Do something on initial load AND whenever the history stack changes
  var sharedTimer = waitUntil(sidebarExists,injectSidebar,tryInterval);
  $(window).bind("popstate", function() {
     waitUntil(sidebarExists,injectSidebar,100,sharedTimer);
  });

 function sidebarExists() {
    return($('.y3').length === 0);
  }

  function injectSidebar() {
      processMessage();
  }