var locationurl = String(document.location);
var url			= '/plug/spider/';
var smartimgtimeout;
var trackCount = 0;
function smarttrack() {
    var referrer;
    try {
        referrer = top.document.referrer;
    } catch (e) {
        referrer = document.referrer;
    }
    var smart_img = new Image();
    smart_img.src = url + 'track.asp?locationurl=' + encodeURIComponent(locationurl) + '&referrer=' + encodeURIComponent(referrer) + '&rnd=' + Math.random();
    trackCount++;
    var interval = trackCount <= 5 ? 6000 : 60000;
    smartimgtimeout = setTimeout(smarttrack, interval);
}
smarttrack();

window.addEventListener('beforeunload',function(){
    clearTimeout(smartimgtimeout);
});
document.addEventListener('visibilitychange',function(){
    if(document.hidden){
        clearTimeout(smartimgtimeout);
    }else{
        trackCount = 0;
        smarttrack();
    }
})