JS之文本的查找跟替换

<script type="text/javascript">
<!--
window.onload = function()
{
 try
 {
  var doc = parent.document;
  var Frm = doc.getElementById( "content" );
  var Obj = doc.body || doc.documentElement;
  if(typeof Frm != "object" || Frm == null)
  {
   Obj.innerHTML = Obj.innerHTML.replace(/2009年下半年/g, "2011年上半年" );
   var Frms = document.getElementsByTagName( "iframe" );
   for( var i in Frms )
   {
    if(Frms[i].src == "header.html")
    {
     Frms[i].id = "content";break;
    }
   }
  }
 }
 catch(E){}
}
-->
</script>