简述JavaScript对传统文档对象模型的支持

<html>
<head>
<title> Document Title </title>
<script type="text/javascript">
<!--
function myFunc()
{
  var ret = document.title;
  alert("Document Title : " + ret );

  var ret = document.URL;
  alert("Document URL : " + ret );

  var ret = document.forms[0];
  alert("Document First Form : " + ret );

  var ret = document.forms[0].elements[1];
  alert("Second element : " + ret );

}
//-->
</script>
</head>
<body>
<h1 id="title">This is main title</h1>
<p>Click the following to see the result:</p>

<form name="FirstForm">
<input type="button" value="Click Me" onclick="myFunc();" />
<input type="button" value="Cancel">
</form>

<form name="SecondForm">
<input type="button" value="Don't ClickMe"/>
</form>

</body>
</html>