1，ajax分为$.ajax()，$.get()，$.post()，$.getJSON() 几种形式，实例如下：
<html>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8">
<script type="application/javascript" src="../js/jquery-1.7.2.js"></script>
<script type="application/javascript">
$(document).ready(function(){
$("#ajaxBut").click(function(){
$.ajax({
'type':'get',
'url':'test4.php',
'dateType':'json',
'data':$("input").serialize(),
'success':function(ret){
alert(ret);
}
});
});
$("#getBut").click(function(){
$.get("test4.php",$("input").serialize(),function(ret){
alert(ret);
});
});
$("#postBut").click(function(){
$.post("test5.php",$("input").serialize(),function(ret){
alert(ret);
});
});
$("#jsonBut").click(function(){
$.getJSON("test4.php",$("input").serialize(),function(ret){
alert(ret);
});
});
});
</script>
<body>
<form>
<h1>user Login</h1>
username:<input type="text" name="user" id="user" /><br/>
password:<input type="password" name="password" id="password"/><br/>
<input type="button" name="but" id = "ajaxBut" value="ajaxLogin" />
<input type="button" name="but" id = "postBut" value="postLogin" />
<input type="button" name="but" id = "getBut" value="getLogin" />
<input type="button" name="but" id = "jsonBut" value="jsonLogin" />
</form>
</body>
</html>
test4.php
<?php
$username = $_GET['user'];
$password = $_GET['password'];
$ret = "fail";
if($username == 'zhangsan' && $password == '123'){
$ret = "success";
}
echo json_encode($ret);
test5.php
<?php
$username = $_POST['user'];
$password = $_POST['password'];
$ret = "fail";
if($username == 'zhangsan' && $password == '123'){
$ret = "success";
}
echo json_encode($ret);
2，ajax跨域获取数据，使用到jsonp，实例如下：
$.getJSON("http://www.ganji.com/test6.php?callback=?", $("input").serialize() , function(data){
if(data){
console.log(data);
}
});
test6.php
$str = 'OK';
$callback = $_GET('callback');
if (!empty($callback)) {
header("content-type: application/x-javascript; charset=UTF-8");
echo $callback . '(' . $str . ')';
} else {
echo $str;
}
}