title: Failed to execute 'requestAnimationFrame' on 'Window': The callback provided as parameter 1 is not a function.
body: <p>Not sure what I'm doing wrong here... </p>
  
  <pre><code>window.requestAnimFrame = function(){
  return (
      window.requestAnimationFrame       || 
      window.webkitRequestAnimationFrame || 
      window.mozRequestAnimationFrame    || 
      window.oRequestAnimationFrame      || 
      window.msRequestAnimationFrame     || 
      function(/* function */ callback){
          window.setTimeout(callback, 1000 / 60);
      }
  );
  }();
  
  function animationSequence(elem, ind) {
      this.ind = ind;
      this.elem = elem;
      this.distance = 450;
      this.duration = 900;
      this.increment = 0;
      this.start = Math.abs(this.ind)*450;
      var requestId = requestAnimFrame(this.animate);
      this.move();
  
      this.move = function() {
          this.elem.style.left = this.start - this.increment + "px";
      }
      this.animate = function() {
          var self = this;
          this.move();
          this.increment += 5;
          if (this.increment &gt;= 450) { 
              if (this.ind == 0) { console.log("true"); this.elem.style.left = "1350px" }
              cancelAnimFrame(requestId);
          }
      }
      // this.animate();
  }
  </code></pre>