json大师请进来，帮助看一下能否取到object长度

[gaowenzhen]

var rsr={"category": {"parent_id": 40740, "name": "\u7f51\u8d2d", "parent": {"parent_id": 40739, "id": 40740, "parent": {"parent_id": 40738, "id": 40739, "parent": {"parent_id": 0, "id": 40738, "name": "\u6d88\u8d39\u7c7b\u578b"}, "name": "\u9ed8\u8ba4\u5206\u7c7b"}, "name": "\u7f51\u8d2d"}, "id": 40741}, "current_page": 1, "total_page": 1, "success": true, "children": []}

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我想取到rsr.category里的每个对像，就是怎么循环每个rsr.category.parent，parent{}数不固定
这个JSON是别处得到的，我自已没法改成[]，请问我可以像取rsr.category.parent.length来for 出来吗

如下我自已写的,取到的都是undefined
for(var intes in rsr.category){
alert(rsr[intes]);
}

[frog8659]

	var obj = eval(rsr);
	 for(var item in obj.category){
    alert(obj.category[item]); 
 }