text: var obj = {
    // 私有属性(js里面是没有严格意义的私有属性)
    _age: 18,
    _eating: function() {},
    set age(value) {
      this._age = value
    },
    get age() {
      return this._age
    }
  }
  
  Object.defineProperties(obj, {
    name: {
      configurable: true,
      enumerable: true,
      writable: true,
      value: "why"
    },
    age: {
      configurable: true,
      enumerable: true,
      get: function() {
        return this._age
      },
      set: function(value) {
        this._age = value
      }
    }
  })
  
  obj.age = 19
  console.log(obj.age)
  
  console.log(obj)
  