[前端] AJAX

 1 <span>输入账号 :</span>
 2 <input id="name" name="name" onkeyup="check()" type="text">  
 3 <span id="checkResult"></span>
 4  
 5 <script>
 6 var xmlhttp;
 7 function check(){
 8   var name = document.getElementById("name").value;
 9   var url = "https://how2j.cn/study/checkName.jsp?name="+name;
10  
11   xmlhttp =new XMLHttpRequest(); 
12   xmlhttp.onreadystatechange=checkResult; //响应函数
13   xmlhttp.open("GET",url,true);   //设置访问的页面
14   xmlhttp.send(null);  //执行访问
15 }
16  
17 function checkResult(){
18   if (xmlhttp.readyState==4 && xmlhttp.status==200)
19     document.getElementById(‘checkResult‘).innerHTML=xmlhttp.responseText;
20   
21 }
22  
23 </script>

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8" isELIgnored="false"%>
 3  
 4 <%
 5     String name = request.getParameter("name");
 6      
 7     if("abc".equals(name))
 8         out.print("<font color=‘red‘>已经存在</font>");
 9     else
10         out.print("<font color=‘green‘>可以使用</font>");
11      
12 %>