每xxxxx毫秒检测一次是否在线, 
TR_COUNT次之后设定改用户为假死状态(即不在当前页面活动,afk..) 
当页面关闭时把停留时间送出, 
/**//* ---------------------------------------------------------------------------- 
* Script Name: online.js 
* Last Modified: 2008-4-13 22:25 
* Author: meyu 
* Copyright (c) 2008 
* Purpose: 跟踪在线时间 
* ----------------------------------------------------------------------------*/ 
function TR_XMLHttpObject(url)...{ 
    this.XMLHttp=null; 
    this.url=url; 
    this.init=function()...{ 
        if(window.XMLHttpRequest)...{ 
            this.XMLHttp=new XMLHttpRequest(); 
        }else if(window.ActiveXObject)...{ 
            this.XMLHttp=new ActiveXObject("Microsoft.XMLHTTP"); 
        } 
    }; 
    this.init(); 
    this.sendData=function(param)...{ 
        with(this.XMLHttp)...{ 
            open('GET',this.url+(param||''),true); 
            send(null); 
        } 
    }; 
} 
if(/flag=flush/i.test(window.location.search))...{ 
    var TR_COUNT=0; 
    var TR_x=new TR_XMLHttpObject(window.location.href.replace(/&?(?:flush_count=)(d+)/i, 
        function(a,d)...{ 
            TR_COUNT=parseInt(d); 
            return ""; 
            }) 
    ); 
    function send()...{ 
        TR_COUNT++; 
        if(TR_COUNT < 120)...{ 
            TR_x.sendData('&flush_count='+TR_COUNT); 
        } 
    } 
    window.setInterval(send,30000); 
    window.onunload=function()...{TR_x.sendData('&flush_count='+TR_COUNT);}; 
}
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