debugging-alert not work in netscape!!

hey everyone, trying to debug this script to get width of browser in netscape/ie, I was trying to get value of widwindow variable to appear in an alert box but having no joy-cant get alert working in Netscape(pretty new to netscape!)
Its in the head section, does this make a difference, I have had alert() working in the body. Can anyone help me with this one..its probably pretty simple I know but its the simple ones that can be the most annoying..

function posob() {
if (document.layers) {
widwindow = parseInt(document.innerWidth);
alert(widwindow);
boxob = document.box;
}
else if (document.all) {
widwindow = parseInt(document.body.clientWidth);
boxob = box.style;
}

widwindow = widwindow – parseInt(boxob.width);
boxob.left = widwindow;

}

cheers

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