AJAX无法访问从php传递的对象数据值

Question

我有一个php.php文件来接收数据然后将结果传回给AJAX，如下所示：

<?php

$p1 = $_POST["p1"];
$c1 = $_POST["c1"];
$resultx['r1'] = "XXX";
$resultx['r2'] = 0;
$resultx['r3'] = 100;
$resultx['r4'] = 1000;

echo json_encode($resultx);

在我的js文件中，我有：

$.ajax({
    url: 'php.php',
    type: 'POST',
    data: {
        p1: 5,
        c1: 100            
    },

    cache: false,
    success: function (resultx) {     
       var result = resultx;
       console.log(result);

        var my1 = document.getElementById('my1');
        var my2 =  document.getElementById('my2');
        var my3 =  document.getElementById('my3');
        var my4 = document.getElementById('my4');           

        my1.textContent = "Id : "+result.r1;
        my2.textContent = "Rank : "+result.r2;
        my3.textContent = "Total players : "+result.r3;
        my4.textContent = "Top credit : "+result.r4;


   },
}); 

my1 my2 my3 my4字段全部打印未定义，即使控制台日志显示的值为：

{"r1":"XXX","r2":0, "r3":100, "r4":1000}

当我更改声明时

var result = resultx;

到

var result = JSON.parse(resultx)

javascript控制台会输出uncaught syntax error unexpected token的错误消息。

请帮忙！