php用ajax为什么只能返回数字
<br />
//提交表单<br />
function subm(){<br />
var user = $('#frm').serialize();<br />
$.ajax({<br />
url: 'b.php',<br />
type: 'POST',<br />
data:user,<br />
contentType:"application/json",<br />
dataType: 'json',<br />
async:false,<br />
beforeSend: function(){<br />
alert('Error loading PHP document');<br />
},<br />
success: function(result){<br />
alert(result);<br />
}<br />
});<br />
}<br />
<br /> <form id="frm" action="" method="post" onsubmit="subm()"><br /> <input<br /> id="user" name="username" /><br /><br /> <input id="password" type="password" name="password" /><br /><br /> <br /> <input type="submit" value="提交" /></form>
