Proxy代理

  var obj = {
    name: 333,
    age: 11
  };
  
  var obj2 = new Proxy(obj, {
    get(target, key) {
       console.log(obj === target)
      // console.log(key)
      return target[key]
    },
    set(target, key, val) {
      // console.log(obj === target)
      // console.log(key, val)
      target[key] = val
    }
  })