js实现ajax

js实现ajax

//创建ajax    var xmlHttp;    function createXMLHttpRequest() {        if (window.XMLHttpRequest) {            xmlHttp = new XMLHttpRequest();        } else {            xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");        }    }    //验证id    function ckId(num){        var pattern=/^[1-9][0-9]{0,9}$/g;        if(!pattern.test(num)){            var idmsg = document.getElementById("idmsg");             idmsg.innerHTML = "";            idmsg.style.color = "red";            idmsg.innerHTML = "编号必须1-10位的数字";            idFlag=false;        }else {            createXMLHttpRequest();            xmlHttp.open("POST", "checkUserOtherNum.do?oldNum=${user.id}&num=" + num);            xmlHttp.onreadystatechange = ckNumCallBack;            xmlHttp.send(null);        }    }    //id回调函数    function ckNumCallBack(){        if (xmlHttp.readyState == 4 && xmlHttp.status == 200) {            var text = xmlHttp.responseText;            var idmsg = document.getElementById("idmsg");            if (text == "false") {                var idmsg=document.getElementById("idmsg");                idmsg.innerHTML = "";                idmsg.style.color = "green";                idmsg.style.fontSize="20px";                idmsg.innerHTML = "ok";                idFlag=true;            } else {                idmsg.innerHTML = "";                idmsg.style.color = "red";                idmsg.innerHTML = "编号已经存在";                idFlag=false;            }        }    }