Syntax
filesystemobject.GetExtensionName(path)
The GetExtensionName() method gets the file extension name for a specified file.
This method takes path as its only parameter.
<html>
<body>
<script language="JScript">
<!--
function getExt()
{
var myObject, ext;
myObject = new ActiveXObject("Scripting.FileSystemObject");
ext = myObject.GetExtensionName("c:\\test.txt");
alert("The extension for the testing file is: " + ext);
}
-->
</script>
Get the extension for the file "testing.txt".
<form name="myForm">
<input type="Button" value="Get Extension" onClick='getExt()'>
</form>
</body>
</html>