页面验证1——ajax异步提交

页面有两个ajax验证，用户名是不是已注册，邮箱是不是已注册

var xmlHttp;
function createXmlHttpRequest() {
    if (window.XMLHttpRequest) {
        xmlHttp = new XMLHttpRequest();

        if (xmlHttp.overrideMimeType) {
            xmlHttp.overrideMimeType("text/xml");
        }
    }
    else if (window.ActiveXObject) {
        try {

            xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");

        }
        catch (e) {

            xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
    }
    if (!xmlHttp) {

        window.alert("你的浏览器不支持创建XMLhttpRequest对象");
    }
    return xmlHttp;
}

var issubmit2 = false;
//一个请求响应处理两个ajax验证请求
function checkEmailAndLogname() {
    url = $("#a").attr("href");
    createXmlHttpRequest();
    url = "./" + url + "?Name=" + document.getElementById("tbUlogname").value + "," + document.getElementById("tbUemail").value + "&Event=CheckUemailAndLogname";

    xmlHttp.open("post", url, true);

    xmlHttp.onreadystatechange = function() { checkEmailAndLognameResult() };

    xmlHttp.send(null);

}

function checkEmailAndLognameResult() {
    if (xmlHttp.readyState == 4)//服务器响应状态
    {
        if (xmlHttp.status == 200)//代码执行状态
        {
            var regExValue = /^([a-zA-Z0-9_-])+@([a-zA-Z0-9_-])+((\.[a-zA-Z0-9_-]{2,3}){1,2})$/;

            var tbemail = document.getElementById("tbUemail").value;
            var flag = regExValue.test(tbemail);
            var pw1 = document.getElementById("tbUlogname").value;
            //            alert(xmlHttp.responseText);
            switch (xmlHttp.responseText) {
                case "1":
                    if (!flag) {
                        $("#img3").attr("src", "../images/16_info.png");

                        $("#A3").attr("innerHTML", "邮箱格式不正确。");
                        $("#tbUemail").css("border", " 2px red solid");
                        issubmit2 = false;
                    }
                    else {
                        $("#img3").attr("src", "../images/fzcg_dh.gif");

                        $("#A3").attr("innerHTML", "");
                        $("#tbUemail").css("border", " 1px #ccc solid");
                        issubmit2 = true;
                    }
                    if (!(pw1.length > 3 && pw1.length < 17)) {

                        $("#img").attr("src", "../images/16_info.png");

                        $("#tt").attr("innerHTML", "用户名应该大于4位小于16位");

                        $("#tbUlogname").css("border", " 2px red solid");
                        issubmit = false;
                    }
                    else {
                        $("#img").attr("src", "../images/fzcg_dh.gif");

                        $("#tt").attr("innerHTML", "");
                        $("#tbUlogname").css("border", " 1px #ccc solid");
                        issubmit = true;
                    }
                    break;
                case "2":
                    if (!flag) {
                        $("#img3").attr("src", "../images/16_info.png");

                        $("#A3").attr("innerHTML", "邮箱格式不正确。");
                    }
                    else {
                        $("#img3").attr("src", "../images/16_info.png");

                        $("#A3").attr("innerHTML", "邮箱已被使用，请更换邮箱再注册。");
                    }
                    $("#tbUemail").css("border", " 2px red solid");

                    if (!(pw1.length > 3 && pw1.length < 17)) {

                        $("#img").attr("src", "../images/16_info.png");

                        $("#tt").attr("innerHTML", "用户名应该大于4位小于16位");

                        $("#tbUlogname").css("border", " 2px red solid");
                        issubmit = false;
                    }
                    else {
                        $("#img").attr("src", "../images/fzcg_dh.gif");

                        $("#tt").attr("innerHTML", "");
                        $("#tbUlogname").css("border", " 1px #ccc solid");
                        issubmit = true;
                    }
                    issubmit = false;
                    break;
                case "3":
                    if (!flag) {
                        $("#img3").attr("src", "../images/16_info.png");

                        $("#A3").attr("innerHTML", "邮箱格式不正确。");
                        $("#tbUemail").css("border", " 2px red solid");
                    }
                    else {
                        $("#img3").attr("src", "../images/fzcg_dh.gif");

                        $("#A3").attr("innerHTML", "");
                        $("#tbUemail").css("border", " 1px #ccc solid");
                    }
                    if (!(pw1.length > 3 && pw1.length < 17)) {

                        $("#img").attr("src", "../images/16_info.png");

                        $("#tt").attr("innerHTML", "用户名应该大于4位小于16位");
                    }
                    else {
                        $("#img").attr("src", "../images/16_info.png");

                        $("#tt").attr("innerHTML", "用户名已存在，可以使用中文");
                    }
                    $("#tbUlogname").css("border", " 2px red solid");
                    issubmit = false;
                    break;
                case "4":
                    if (!flag) {
                        $("#img3").attr("src", "../images/16_info.png");

                        $("#A3").attr("innerHTML", "邮箱格式不正确。");
                    }
                    else {
                        $("#img3").attr("src", "../images/16_info.png");

                        $("#A3").attr("innerHTML", "邮箱已被使用，请更换邮箱再注册。");
                    }

                    $("#tbUemail").css("border", " 2px red solid");

                    if (!(pw1.length > 3 && pw1.length < 17)) {

                        $("#img").attr("src", "../images/16_info.png");

                        $("#tt").attr("innerHTML", "用户名应该大于4位小于16位");
                    }
                    else {
                        $("#img").attr("src", "../images/16_info.png");

                        $("#tt").attr("innerHTML", "用户名已存在，可以使用中文");
                    }

                    $("#tbUlogname").css("border", " 2px red solid");
                    issubmit = false;
                    break;

            }
        }

    }
}

在页面提交时异步验证用户名和邮箱，两个异步请求后一个会覆盖前一个请求，更改在提交两个验证用一次异步请求，根据相应结果判断。