title: filter: alpha in javascript syntax
body: <p>If I'm changing opacity via CSS I use two versions:</p>
  
  <pre><code>opacity: 1;
  filter: alpha(opacity=100); /*IE8 &amp; earlier*/
  </code></pre>
  
  <p>If I'm changing opacity via javascript, I know this version:</p>
  
  <pre><code>object.style.opacity="xx"
  </code></pre>
  
  <p>which I believe I can also prefix with -webkit-, -moz-, and -o-, but is there a javascript equivalent for filter: alpha(opacity) or does style.opacity cover IE8 &amp; earlier? I am not using JQuery or any other libraries, just javascript and CSS.</p>
  
  <p>Thanks</p>