Ajax implements asynchronous username verification function

When the user fills in the account and switches to the password box, use ajax to verify the availability of the account. This article mainly introduces the asynchronous user name verification function of Ajax in detail. Friends who are interested in ajax can refer to it

The layout is relatively simple first. The rendering is as follows

ajax function:

When the user fills in the account and switches to the password box, use ajax to verify the availability of the account. The verification method is as follows: first create an XMLHTTPRequest object, then send the information that needs to be verified (user name) to the server for verification, and finally determine whether the user name is available based on the status returned by the server.

function checkAccount(){
var xmlhttp;
var name = document.getElementById("account").value;
if (window.XMLHttpRequest)
 xmlhttp=new XMLHttpRequest();
else
 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
 
xmlhttp.open("GET","login.php?account="+name,true);
xmlhttp.send();
 
xmlhttp.onreadystatechange=function(){
 if (xmlhttp.readyState==4 && xmlhttp.status==200)
  document.getElementById("accountStatus").innerHTML=xmlhttp.responseText;
}

Running results

##Code implementation

使用Ajax实现异步登陆验证

账 号：


密 码：

<?php
  $con = mysqli_connect("localhost","root","GDHL007","sysu");
 
  if(!empty($_GET[&#39;account&#39;])){
    $sql1 = &#39;select * from login where account = "&#39;.$_GET[&#39;account&#39;].&#39;"&#39;;
    //数据库操作
    $result1 = mysqli_query($con,$sql1);
    if(mysqli_num_rows($result1)>0)
      echo &#39;<font style="color:#00FF00;">该用户存在</font>&#39;;
    else 
      echo &#39;<font style="color:#FF0000;">该用户不存在</font>&#39;;
    mysqli_close($con);
  }else
    echo &#39;<font style="color:#FF0000;">用户名不能为空</font>&#39;;
 
?>

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