ajax的创建 ajax.js
//创建ajax对象 function c_xmlhttp(){ var xmlhttp=null; if(window.XMLHttpRequest){ xmlhttp= new XMLHttpRequest; //如果请求的不是xml 则将它转为xml if(xmlhttp.overrideMime Type){ xmlhttp.overrideMime Type("text/html") } } else if(window.ActiveXObiect){ try{ xmlhttp=new ActiveXobject(Wsxml2.XMLHTTP); }catch(e){ try{ xmlhttp=new ActiveXObject(Microsoft.XNLHTTP); }catch(e){} } } return xmlhttp; } xmlhttp=c_xmlhttp(); function getdata(id){ xmlhttp.open('GET','index.php?id='+id,true); xmlhttp.onreadystatechange=handle; xmlhttp.send(); } function handle(){ if(xmlhttp.readystate==4){ if(xmlhttp.status==200){ var text=xmlhttp.responseText; document.getElementById('content').innerHTML=text; } } }
inddex.html
<html> <head> <title>测试ajax</title> <script type="text/javascript" src="ajax.js"></script> </head> <body> 名称: <input type="text" name='name' value="" onclick="getdate(this.value)"> <div id="content"></div> </body> </html>
index.php
<?php if(isset($_GET['id'])){ $id=$_GET['id']; $mysqli=new mysqli('loclhost','root','my123','myuser') or die("链接失败!"); $query=$mysqli->query("select *from user where name=".$id); if(is_array(mysqli_fetch_row($query))){ echo "该用户已存在"; }else echo "可以使用"; } ?>