javascript计算用户打开网页的停留时间

　　<SCRIPT LANGUAGE="JAVASCRIPT">

　　<!--

　　var ap_name = navigator.appName;

　　var ap_vinfo = navigator.appVersion;

　　var ap_ver = parseFloat(ap_vinfo.substring(0,ap_vinfo.indexOf('(')));

　　var time_start = new Date();

　　var clock_start = time_start.getTime();

　　var dl_ok=false;

　　function init ()

　　{

　　if(ap_name=="Netscape" && ap_ver>=3.0)

　　dl_ok=true;

　　return true;

　　}

　　function get_time_spent ()

　　{

　　var time_now = new Date();

　　return((time_now.getTime() - clock_start)/1000);

　　}

　　function show_secs () // show the time user spent on the side

　　{

　　var i_total_secs = Math.round(get_time_spent());

　　var i_secs_spent = i_total_secs % 60;

　　var i_mins_spent = Math.round((i_total_secs-30)/60);

　　var s_secs_spent = "" + ((i_secs_spent>9) ? i_secs_spent : "0" + i_secs_spent);

　　var s_mins_spent ="" + ((i_mins_spent>9) ? i_mins_spent : "0" + i_mins_spent);

　　document.fm0.time_spent.value = s_mins_spent + ":" + s_secs_spent;

　　window.setTimeout('show_secs()',1000);

　　}

　　// -->

　　</SCRIPT>