<script type="text/javascript" src="http://libs.baidu.com/jquery/1.9.0/jquery.min.js"></script>

<script type="text/javascript">
// 帐号修改
function accountChange(account)
{
    if(account != '') {
        $.ajax({
            type: 'POST',
            url: '1.php',
            data: {account: account},
            dataType: 'json',
            success: function(response) {
                if(response['code'] == 0 && response['account'] == account) {
                    $('#check').text('Success');
                } else {
                    $('#check').text('Fail');
                }
            },
            error: function(XMLHttpRequest, textStatus, errorThrown) {
                // 请求失败
            }
        });
    }
}

</script>


帐号: <input type="text" onchange="accountChange($(this).val());" /><label id="check"></label>
<br /><br />
密码: <input type="password" />

<?php

echo json_encode(array('code' => 0, 'account' => $_POST['account']));