需要当用户登录出错时给出提示，请问我该怎么设计？

Question

window["lib"]["lognModule"] = (function () {var uniqueLogn;function constructor() {var lognHtml = "<div id='light'>";lognHtml = lognHtml + "<div id='tabsHead'><a class='curtab' id='tabs1' href='javascript:showTab(\"tabs1\",\"tabContent1\")'>登陆</a>";lognHtml = lognHtml + "<a class='tabs' id='tabs2' href='javascript:showTab(\"tabs2\",\"tabContent2\")'>注册</a>";lognHtml = lognHtml + "<a style='float:right;' href='javascript:cancle()' onclick=''>X</a>";lognHtml = lognHtml + "</div><div id='tabContent1' style='display:block;background-color: white;'>";lognHtml = lognHtml + "<table style='hight:270px;backgroud:white;'><tr><td>Username:</td><td><input id='UsernameID' type='text' /></td></tr>";lognHtml = lognHtml + "<tr><td>Password:</td><td><input id='PasswordID' type='password'/></td></tr>";lognHtml = lognHtml + "";lognHtml = lognHtml + "<tr><td colspan='2' align='center'><input onclick='logIn()' value='OK' type='button' /></td></tr>";lognHtml = lognHtml + "</table></div><div id='tabContent2' style='display:none;'><iframe id='registerIframe' style='background-color:white;' height='270px' frameborder='0' scrolling='no' src='register.htm'></iframe></div></div>";return lognHtml;function ResponseForLogIn(ResTxt) {var tmp = getValueFromContent(ResTxt, "result");switch (tmp) {case "nouser":$("waitSecondID").style.display = "";if (Sys.ie) {second = $("totalSecond").innerText;}else {second = $("totalSecond").textContent;}setInterval(function () {redirect(url, second);second--;}, 1000);break;case "verified":var temp = getValueFromContent(ResTxt, "data");g_AllData = eval('(' + temp + ')');createWebTable();hideTab($('light'));minimize($('fade'));SetCookie("username", g_AllData.page.Muser.Us, 30, "/", true);setUserInfo();break;case "incorrect username or password.":var a = 0;break;}}谢谢！

Answer 1

在文本框的后面放一个span给它加一个ID然后用js 的document.getElementByID("id名");获取此span
var d=document.getElementById('id名');然后设置出错信息 d.setInnerHTML="用户名错误";即可！！

Answer 2

<div id="msg"></div>
function login(){
var msg=document.getElementById("msg");
msg.innerHTML="用户名错误！";
}

Answer 3

alert("密码错误")