var antispam = 'false';
<body onLoad="main();" onclick="antispam = 'true'" onkeyup="antispam = 'true'" >
<form method="GET" action="antispam.php">
<input type="hidden" name="antispam" id="antispam" value="false" />
How about you explain what it is you are actually trying to achieve? (I don't mean, like the thread title - I mean the actual end goal; what functionality are you trying to get?)
If you're trying to catch people's mouse clicks and prevent right-click etc. then forget it - such techniques are so easy to get around.
Don't know exactly what you want to do but I'd recommend downloading jQuery, it'll make your life easier and your code more cross-browser compatible. To set a form value with jQuery, you would just do $('#antispam').val('My Value!');
it is for antispam, to prevent bot submission.