AJAX GET requests being cached

Question

Due to some browsers caching AJAX GET requests I have added the following bit of code.

if(k){
    x.open('POST',c,true); x.setRequestHeader('Content-type','application/x-www-form-urlencoded'); x.send(k)
}else{
    if(c.indexOf('?') == -1){c += '?'}else{c += '&'}
    c += 'timer=' + new Date().getTime();
    x.open('GET',c,true); x.send(null)
}

This is a great script.  Thanks very much for your efforts.

Steve