title: Mootools morph using variable
body: <p>I'm creating a javascript function for my website that accepts several parameters, and then uses said parameters to perform a morph. Rather normal stuff, however the morph doesn't work. It seems that by getting the css attribute I want to morph (ie <code>height</code>) as a variable, I am bugging.</p>
  
  <p>Base code being used:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>window.addEvent('load', function() {
      var box = $('box');
      var sfx = new Fx.Morph(box, {
          duration: 1000,
          transition: Fx.Transitions.linear
      });
      
      var cssParam = 'height';
      var endVal = '100';
      
      sfx.start({cssParam endVal});
      console.log(sfx);
  });</code></pre>
  <pre class="snippet-code-css lang-css prettyprint-override"><code>#box {
      width:200px;
      height:200px;
      background-color: #FFFFFF;
      border: 1px solid #000000;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div id="box"&gt;&lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>The morph is taking the variable <code>cssParam</code> literally, and is trying to morph <code>cssParam</code> to 100. Obviously I am doing this wrong, how do I fix this issue?</p>