XMLHttpRequest cannot load JSONP

<script type="text/javascript" >
        $.ajax({
            dataType:"JSONP",
            jsonp:"callback",         //请求自动带上callback参数,callback值为jsonpCallback的值
            jsonpCallback:‘login‘,    //接口服务器应该返回字符串数据格式:login(JSON数据)
            type:‘post‘,
            url:"http://mm.web.com/api.php",
            data:{},     //请求数据
            success:function(response){
                console.log(response);
            },
            error:function(e){
                alert(e.status+‘,‘+ e.statusText);
            }
        })
    </script>

<?php

    //跨域
    $response[‘status‘] = 200;
    $response[‘msg‘] = "success";
    echo "login(".json_encode($response).")";