jquery ajax 登录验证

$(document).ready(function(){
    $("#form").submit(function(){
        login();
        return false;
    });
});
function login()
{
   var user = $("#username").val();
   var pass = $("#password").val();
   if (user == "")
   {
      $("#msg").text("请输入登录用户名");
      $("#user").focus();
      return false;
   }
   if(pass == "")
   {
      $("#msg").text("请输入登录密码");
      $("#pass").focus();
      return false;
   }

   $.ajax({
    type: "POST",
    url: "test.php",
    data: "username=" + user + "&password=" + pass,
    beforeSend: function(){
    $("#msg").text("登录中，请稍候......");
    },
    success: function(msg){
    if(msg == "success"){
        $("#msg").text("登录成功，欢迎" + user + "回来！正在进入你的空间......");
    }else {
        $("#msg").text("没有此用户或者密码不正确！");
    }
    }
   });
}

 <script type="text/javascript" src="js/jquery.js"></script>
 <script type="text/javascript"  src="js/ajax_login.js"></script>

      <div id="login">
      <form method="post" action="" id="form" name="form">
      <ul>
      <li>名字：<input type="text" name="username" id="username" size="30" maxlength="200"></li>
      <li>密码：<input type="password" name="password" id="password" size="30" maxlength="200"></li>
      <li>
        <input type="submit" style="border:0" value="submit" />&nbsp;&nbsp;<INPUT TYPE="reset" value="resite" style="border:0">
      </li>
      <li id="msg"></li>
      </ul>
      </form>
      </div>