对象循环，修改对象属性，用于修改后端返回数据字段

var json = [{ "title": "0-0", "key": "叶子", "children": [{ "title": "0-0-0", "key": "0-0-0", "children": [{ "title": "0-0-0-0", "key": "0-0-0-0" }, { "title": "0-0-0-1", "key": "0-0-0-1" }, { "title": "0-0-0-2", "key": "0-0-0-2" }] }, { "title": "0-0-1", "key": "0-0-1", "children": [{ "title": "0-0-1-0", "key": "0-0-1-0" }, { "title": "0-0-1-1", "key": "0-0-1-1" }, { "title": "0-0-1-2", "key": "0-0-1-2" }] }, { "title": "0-0-2", "key": "0-0-2" }] }, { "title": "0-1", "key": "0-1", "children": [{ "title": "0-1-0", "key": "0-1-0", "children": [{ "title": "0-1-0-0", "key": "0-1-0-0" }, { "title": "0-1-0-1", "key": "0-1-0-1" }, { "title": "0-1-0-2", "key": "0-1-0-2" }] }, { "title": "0-1-1", "key": "0-1-1", "children": [{ "title": "0-1-1-0", "key": "0-1-1-0" }, { "title": "0-1-1-1", "key": "0-1-1-1" }, { "title": "0-1-1-2", "key": "0-1-1-2" }] }, { "title": "0-1-2", "key": "0-1-2" }] }, { "title": "0-2", "key": "0-2" }]
var json2 = {};
function copy(obj) {
  for (var name in obj) {
    if (typeof obj[name] === "object") { //先判断一下obj[name]是不是一个对象
      if (obj.key) {
        obj['new'] = obj.key;
      }
      copy(obj[name]); //然后来无限调用函数自己 递归思想
    } else {
      if (obj.key) {
        obj['new'] = obj.key;
      }  //如果不是对象，直接等于即可，不会发生引用。
    }
  }
  return obj; //然后在把复制好的对象给return出去
}
json2 = copy(json)