163 AJAX Tab

                    ocontent.innerHTML=xhttp.responseText; 
                    ajccache[url]=ocontent.innerHTML; 
                } 
            } 
        xhttp.open("GET",url,true); 
        xhttp.send(null); 
    }else{ 
        ocontent.innerHTML=ajccache[url]; 
    } 
} 
window.onerror=function(){return true}

具体使用方法,看www.163.com用的