這篇文章用JS顯示表單的登錄以及驗證和對鍵盤的監聽，這里有兩種方法，一種是無需用戶驗證直接登錄，一種是需要賬戶密碼匹配才可登錄。

1. html代碼

<div class="content">  <div class="login-wrap">    <form id="user_login" action="">      <h3>登 錄</h3>      <input class="name" name="" id="accountName" type="text" placeholder="請輸入用戶名">      <input class="code" name="password" id="password" type="password" placeholder="請輸入密碼">      <div class="btn">        <input type="button" id="submit" class="submit" value="登錄" onclick="return check(this.form);">        <input type="reset" id="reset" class="reset" value="重置" >      </div>		<div id="CheckMsg" class="msg"></div>    </form>  </div></div>

2.CSS樣式

.content{	padding:0 auto;  margin: 0 auto;  height: 450px;  width: 100%;  background: url(../Image/Login-Img/login_bg.jpg) no-repeat center;  background-size:100% 450px ;  margin-top: 25px;}.login-wrap{  position: absolute;  width:320px;  height: 300px;  border-radius: 10px;  -webkit-border-radius: 10px;  -moz-border-radius: 10px;  right:200px;  margin-top: 75px;  background: url("../Image/Login-Img/form_bg.png") no-repeat;  background-size: 100%;}.login-wrap h3{  color:#fff;  font-size: 18px;  text-align: center;}.name,.code{  border:1px solid #fff;  width:230px;  height: 40px;  margin-left: 25px;  margin-bottom: 20px;  padding-left: 40px;}.name{  background: url("../Image/Login-Img/user.png") no-repeat left;  background-position-x:12px;}.code{  background: url("../Image/Login-Img/passwd.png") no-repeat left;  background-position-x:12px;}.btn input{  height: 40px;  width: 120px;  float: left;  margin-right: 25px;  border:none;  color:#fff;  font-size: 16px;  -webkit-border-radius: 10px;  -moz-border-radius: 10px;  border-radius: 10px;  margin-top: 10px;  cursor: pointer;}input:active{border-color:#147a62}.submit{background: #ea8c37;margin-left: 25px;}.reset{background: #bbb;}/**錯誤信息提醒**/.msg{  color: #ea8c37;  font-size: 14px;  padding-left: 40px;  padding-top: 10px;  clear: both;  font-weight: bold;}

3.JS代碼

//驗證表單是否為空，若為空則將焦點聚焦在input表單上，否則表單通過，登錄成功function check(form){  var accountName = $("#accountName"),$password = $("#password");  var accountName = accountName.val(),password = $password.val();  if(!accountName || accountName == ""){    showMsg("請輸入用戶名");    form.accountName.focus ();    return false;  }  if(!password || password == ""){    showMsg("請輸入密碼");    form.password.focus ();    return false;  }//這里為用ajax獲取用戶信息并進行驗證，如果賬戶密碼不匹配則登錄失敗，如不需要驗證用戶信息，這段可不寫 $.ajax({    url : systemURL,// 獲取自己系統后臺用戶信息接口    data :{"password":password,"accountName":accountName},    type : "GET",    dataType: "json",    success : function(data) {      if (data){        if (data.code == "1111") { //判斷返回值，這里根據的業務內容可做調整            setTimeout(function () {//做延時以便顯示登錄狀態值              showMsg("正在登錄中...");              console.log(data);              window.location.href = url;//指向登錄的頁面地址            },100)          } else {            showMsg(data.message);//顯示登錄失敗的原因            return false;          }        }      },      error : function(data){        showMsg(data.message);      }  });}//錯誤信息提醒function showMsg(msg){  $("#CheckMsg").text(msg);}//監聽回車鍵提交$(function(){  document.onkeydown=keyDownSearch;  function keyDownSearch(e) {    // 兼容FF和IE和Opera    var theEvent = e || window.event;    var code = theEvent.keyCode || theEvent.which || theEvent.charCode;    if (code == 13) {      $('#submit').click();//具體處理函數      return false;    }    return true;  }});