AJAX初级聊天室代码

          if(nowNum != "0" && useMag != ""){
                if(useName != ""){
                    var lis = "用户"+ useName + "说：" + useMag + " ["+ useIp + "]"
                }else{
                    var lis = "用户 ["+ useIp + "] 说：" + useMag
                }
            }else{
                var lis = "用户 ["+ useIp + "] 进入聊天室！"
            }
            //var newp = document.createElement("p")
            //newp.innerHTML = lis
            //getId("chatmain").appendChild(newp)
            getId("chatmain").innerHTML += lis + "<br />"
        }
        innerSize()
    }
}
function getTag(response,i,objTagName){
    try{
        var nodeV = response.getElementsByTagName(objTagName)[i].firstChild.nodeValue;
    }catch(e){
        var nodeV = ""
    }
    return nodeV;
}
var overs
function innerSize(){
    if(overs != 1){
        if(getId("chatmain").offsetHeight < getId("outmain").offsetHeight){
            getId("chatmain").style.marginTop = getId("outmain").offsetHeight - getId("chatmain").offsetHeight +"px";
        }else{
            getId("chatmain").scrollIntoView(false)    
        }
    }
}
window.onload = function(){
    getId("outs").onmousedown = function(){
        overs = 1
    }
    getId("outs").onmouseout = function(){
        overs = 0
        focs()
    }
    getName(