I'm trying to set the disabled flag on a input element. If you know of an easier way, please. Othwise, what is wrong with this?

Code:
<html>
  <head>
    <title>Test Page</title>
    <script type="text/javascript">
      function foo() {
        alert(document.getElementByID("myInput").nodeName);
      }
    </script>
  </head>
  <body>
    <form name="myForm">
      <input id="myInput" type="text" size="8" value="2">
    </form>
    <p onclick="javascript:foo();">Click Me</p>
  </body>
</html>
I can't get it to return nodeName, much less can I try to setAttributeNode, which may not even be what I need to do.