reg.html
<!DOCTYPE HTML>
<html>
<head>
<title> ajax </title>
<meta charset="utf-8"/>
<script type="text/javascript">
var httpAjax = new XMLHttpRequest();
function checkUser(uname){
if(uname == ""){
return false;
}
httpAjax.onreadystatechange = function(){
if(httpAjax.readyState == 4 && httpAjax.status == 200){
var res = httpAjax.responseText;
res = eval("("+res+")");
var sp = document.getElementById("sp");
if(res.status == 1){
sp.innerHTML = "<font color='red'>"+res.info+"</font>";
var _html ="";
for(var i in res['data']){
_html += "<p>"+res['data'][i]+"</p>"
}
var myobject = document.getElementById('mydiv');
myobject.innerHTML = _html;
}else{
sp.innerHTML = "<font color='green'>"+res.info+"</font>";
}
}
}
httpAjax.open("post","user.php",true);
httpAjax.setRequestHeader("content-TYPE","application/x-www-form-urlencoded");
var data = "uname="+uname; //user.php?uname="1"&pwd="123","uname=" 是參數,+是連接參數連接變量的用的，uname是js中的一個不帶$的變量，也就是值
httpAjax.send(data);
}
</script>
</head>
<body>
<input type="text" id="username" class="username" name="username" onchange="checkUser(this.value)"/><span id="sp"></span>
<div id ="mydiv" style="width:200px;height:200px;border:1px red solid">
</div>
</body>
</html>user.php
<?php
header("content-type:text/html;charset=utf-8");
$pdo = new PDO("mysql:host=localhost;dbname=tk106","root","");
$pdo->exec("set names utf8");
$uname = $_REQUEST["uname"];//post傳值，這裏要改爲REQUEST
$sql = "select * from stu_info where sname='".$uname."'";
$data = $pdo->query($sql)->fetch(PDO::FETCH_ASSOC);
if($data){
$list['status']=1;
$list['info']="已經註冊";
$list['data']=$data;
echo json_encode($list);
}else{
$list['status']=0;
$list['info']="未註冊";
$list['data']=="";
echo json_encode($list);
}
?>