Because browsers other than IE don't create global variables for every part of the page/DOM, you need to qualify references to the form and its elements in non-IE browsers. You can do this either by creating a form reference and passing that to methods, or by using an absolute reference to the document.forms collection in your code. For example:
// the code below works fine in IE.
<HTML>
<SCRIPT language="javascript">
function OnLoad()
{
//Works fine in IE and not in Firefox
frmName.SearchButton.disabled = true
//Replace the above line with the below one
//Works fine in both IE and Firefox
document.frmName.SearchButton.disabled = true
}
</SCRIPT>
<BODY onLoad = "onLoad()">
<form name="frmName">
<input id="SearchButton" name="SearchButton" type="button">
</BODY>
</HTML>