AJAX implements the function of detecting user names without refreshing-JS Tutorial-php.cn

AJAX implements the function of detecting user names without refreshing

亚连

Release： 2018-05-22 11:58:55

Original

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This article mainly introduces the AJAX non-refresh user name detection function in detail, which has certain reference value. Interested friends can refer to it

Let’s take a look at the schematic diagram first

<!DOCTYPE html>
<html>
 <head>
  <meta charset="utf-8" />
  <title>ajax无刷新检测</title>
  <style type="text/css">
   body{margin:0;padding:0;}.content{width:800px;margin:0 auto;}ul,li{list-style: none;margin:0;padding:0;}
   tr{width:200px;}td{width:80px;padding:5px 0;}td input,textarea{border: 1px solid #79ABFE;} 
  </style>
 </head>
 <body>
  <p class="content">
   <script>
    myXmlHttpRequest.ContentType=("text/xml;charset=UTF-8");
    //创建ajax引擎(1号线)
    function getXmlHttpObject(){   
     var xmlHttpRequest;
     //不同浏览器获取对象xmlHttpRequest方法不一样
     if(window.ActiveXObject){
      xmlHttpRequest=new ActiveXObject("Microsoft.XMLHTTP");
     }else{
      xmlHttpRequest=new XMLHttpRequest();
     }
     return xmlHttpRequest;
    }
    //验证用户名是否存在
    var myXmlHttpRequest="";//因为chuli也用到了,所以要定义为全局变量 
    //创建方法(2号线 http请求)
    function checkName(){
     //创建对象 
     myXmlHttpRequest=getXmlHttpObject();
     //判断是否创建ok
     if(myXmlHttpRequest){
      //通过myXmlHttpRequest对象发送请求到服务器的某个页面 
      var url="./registerPro1.php";
      //要发送的数据
      var data="username="+$(&#39;username&#39;).value;
      //打开请求
      myXmlHttpRequest.open("post",url,true);//ture表示使用异步机制
      //POST方法
      myXmlHttpRequest.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
      //指定回调函数,chuli是函数名(registerPro里的数据返回给chuli函数)
      myXmlHttpRequest.onreadystatechange=chuli;
      //开始发送数据,如果是get请求则填入null即可,如果是post请求则填入实际的数据
      myXmlHttpRequest.send(data);
     }
    }
    //回调函数(4号线)
    function chuli(){
     //取出从registerPro.php页面返回的数据(4表示完成,200表示成功)
     if(myXmlHttpRequest.readyState==4){
      if(myXmlHttpRequest.status==200){
      //①、取出值,根据返回信息的格式定 text(html)
      //$(&#39;result&#39;).value=myXmlHttpRequest.responseText;
      //②、取出xml格式数据(解析)
      //获取mes节点、这里的mes返回的是节点列表(不知道有几个mes)
      //var mes=myXmlHttpRequest.responseXML.getElementsByTagName("mes");
      //取出mes节点值
      //mes[0]->表示取出第一个mes节点
      //mes[0].childNodes[0]->表示取出mes节点的第一个子节点
      //var mes_val=mes[0].childNodes[0].nodeValue;
      //$("result").value=mes_val; 
      //③、json格式
      //var mes=myXmlHttpRequest.responseText;
      //使用eval函数,将mes字串转为对象
      //var mes_obj=eval("("+mes+")");
      //$(&#39;result&#39;).value=mes_obj.res;
      //③+、json格式扩展
      var mes=myXmlHttpRequest.responseText;
      var mes_obj=eval("("+mes+")");
      $(&#39;result&#39;).value=mes_obj[0].res;
      }
     }
    }  
    //封装一个函数,通过id号获取对象
    function $(id){
     return document.getElementById(id);
    } 
   </script>
   <br/>
   <strong style="color:red">发表留言</strong>
   <form action="#" method="POST" name="frm">
   <table cellpadding="0" cellspacing="0" >
    <tr>
     <td >留言标题:</td>
     <td><input type="text" name="title" autocomplete="off"/></td>
    </tr>
    <tr>
     <td>网名:</td>
     <td>
      <input id="username" onkeyup="checkName();" type="text" name="username" autocomplete="off"/>
      <td><input id="result" type="text" style="width:110px;font-size: 12px;border-width:0;" ></td> 
     </td>
    </tr>
    <tr>
     <td>留言内容:</td>
     <td><textarea name="content" cols="26" rows="5" autocomplete="off"/ onclick="showNotice(this)"></textarea></td>
    </tr>
    <tr>
     <td></td>
     <td><input class="btn" type="submit" name="submit" value="提交"/></td>
    </tr>
   </table>
   </form>
  </p> 
 </body>
</html>

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registerPro1.php

<?php
 //将数据(text格式,xml格式,json格式)返回到ajax引擎(3号线 http响应 )
 
 //header("Content-Type: text/xml; charset=utf-8"); //告诉浏览器,返回的是xml格式
 header("Content-Type: text/html; charset=utf-8"); //告诉浏览器,返回的是text/json格式
 $username = $_POST["username"];
 //①
// if($username=="abc"){
//  echo &#39;网名不可用&#39;;
// }else{
//  echo &#39;网名可用&#39;;
// }
 //②
// $info="";
// if($username=="abc"){
//  $info.="<res><mes>网名不可用</mes></res>";
// }else{
//  $info.="<res><mes>网名可用</mes></res>";
// }
// echo $info;
 //③
// $info="";
// if($username=="abc"){
//  //这里的$info返回的是一个字串
//  $info.=&#39;{"res":"不可用","id":"123","age":"5"}&#39;;
// }else{
//  $info.=&#39;{"res":"可用","id":"3","age":"1"}&#39;;
// }
// echo $info;
 //③+
 $info="";
 if($username=="abc"){
  //这里的$info返回的是一个字串
  $info.=&#39;[{"res":"不可用","id":"123","age":"5"},{"res":"abc不可用","id":"3","age":"0"}]&#39;;
 }else{
  $info.=&#39;[{"res":"可用","id":"1","age":"15"},{"res":"可用","id":"83","age":"9"}]&#39;;
 }
 echo $info;
?>

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The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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