JavaScript Tutorial/MS JScript/win32
@_win32
The @_win32 variable determines if a win32 system is being used. When the variable is not true, it is defined as NaN.
<html>
<script language="JScript">
<!--
@if (@_win32)
alert("You are using a win32 system.");
@else
alert("You are NOT using a win32 system.");
@end
-->
</script>
</html>