var xmlhttp; 
try{ 
    xmlhttp= new ActiveXObject('Msxml2.XMLHTTP'); 
}catch(e){ 
    try{ 
        xmlhttp= new ActiveXObject('Microsoft.XMLHTTP'); 
    }catch(e){ 
        try{ 
            xmlhttp= new XMLHttpRequest(); 
        }catch(e){} 
    } 
} 

function getPart(url){ 
    xmlhttp.open("get",url,true); 
    xmlhttp.onreadystatechange = function(){ 
        if(xmlhttp.readyState == 4) 
        { 
            if(xmlhttp.status == 200) 
            { 
                if(xmlhttp.responseText!=""){ 
                    document.getElementById("ajax").innerHTML = unescape(xmlhttp.responseText);        
                } 
            } 
            else{ 
                document.getElementById("ajax").innerHTML = "Êý¾ÝÔØÈë³ö´í"; 
            } 
        } 
    } 
    xmlhttp.setRequestHeader("If-Modified-Since","0"); 
    xmlhttp.send(null); 
} 
setInterval("getPart('ji.php')",1000);