title: Mootools Javascript can't push to array
body: <p>I have an array set with the heights of each hidden div, but when I use it, the div instantly jumps down, rather than slowly sliding as when there is a literal number.</p>
  
  <hr>
  
  <p><strong>EDIT:</strong> testing seems to reveal that it's a problem with the push method, as <code>content_height.push(item.getElement('.moreInfo').offsetHeight);alert(content_height[i]);</code>gives undefined, but <code>alert(item.getElement('.moreInfo').offsetHeight);</code> gives the correct values</p>
  
  <hr>
  
  <p>Javascript:</p>
  
  <pre><code>window.addEvent('domready', function(){
  
   var content_height = [];i=0;
  
   $$( '.bio_accordion' ).each(function(item){
    i++;
    content_height.push( item.getElement('.moreInfo').offsetHeight);
    var thisSlider = new Fx.Slide( item.getElement( '.moreInfo' ), { mode: 'horizontal' } );
    thisSlider.hide();
  
  
    item.getElement('.moreInfo').set('tween').tween('height', '0px');
  
    var morph = new Fx.Morph(item.getElement( '.divToggle' ));
    var selected = 0;
    item.getElement( '.divToggle' ).addEvents({
    'mouseenter': function(){
     if(!selected) this.morph('.div_highlight');
    },
  
    'mouseleave': function(){
     if(!selected) {
      this.morph('.divToggle');
     }
    },
  
    'click': function(){
     if (!selected){
      if (this.getElement('.symbol').innerHTML == '+')
      this.getElement('.symbol').innerHTML = '-';
      else
      this.getElement('.symbol').innerHTML = '+';
      item.getElement('.moreInfo').set('tween', {
       duration: 1500,
       transition: Fx.Transitions.Bounce.easeOut
      }).tween('height', content_height[i]); //replacing this with '650' keeps it smooth
      selected = 1;
      thisSlider.slideIn();
     }
     else{
      if (this.getElement('.symbol').innerHTML == '+')
      this.getElement('.symbol').innerHTML = '-';
      else
      this.getElement('.symbol').innerHTML = '+';
      thisSlider.slideOut();
      item.getElement('.moreInfo').set('tween', {
       duration: 1000,
       transition: Fx.Transitions.Bounce.easeOut
      }).tween('height', '0px');
      selected = 0;
     }
    }
    });
  
   } );
  
  
  
  
  });
  </code></pre>
  
  <p>Why could this be? Thanks so much!</p>