对象扩展

    let obj = { brand: '华为', price: 1999 };
    Object.defineProperty(obj, 'id', { value: 1 })
    Object.defineProperty(obj, 'price', { configurable: false })
    console.log(Object.keys(obj));  // ['brand','price']
    for (let k in obj) {
      console.log(k);          // brand price
    }
    obj.price = 999;
    delete obj['price']
    console.log(obj);   // { brand: '华为', price: 1999,id: 1}

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      let obj = {
        name:"why",
        age: 18
      }

      Object.defineProperty(obj,"name",{
        configurable: false,  // name属性特性不可修改
        enumerable: false,    // name属性不可枚举
        writable: false,      // 不能被赋值运算符改变
      })

      delete obj.name
      console.log(obj);  // {name: 'rio', age: 20}
      console.log(Object.keys(obj)); // ['age']
      obj.name = 'RIO'
      console.log(obj);  // {name: 'rio', age: 20}
------------------------------------------------------
      let obj = {
        name:"rio",
        age: 20
      }

      Object.defineProperty(obj,"name",{
        value: 'RIO', // 读取属性时会返回该值，修改属性时，会对其进行修改;
      })
      console.log(obj);  // {name: 'RIO', age: 20}

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    let obj = {
      a: 1,
      b: 'qwe',
      c:[],
    }

    Object.prototype.d = "qwe"

    for(let o in obj){
      console.log(o);  // a b c d 
    }

    console.log(Object.keys(obj));  // ['a','b','c']

    console.log(obj.hasOwnProperty('a'));  // true
    console.log(obj.hasOwnProperty('d'));  // false

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      let obj = {
        name: "rio"
      }

      var _name = ""
      Object.defineProperty(obj,'name',{
        configurable: true,
        enumerable: false,
        set:function(value){
          console.log("set " + value);
          _name = value
        },
        get:function(){
          console.log("get!"); 
          return _name
        }
      })

      obj.name = 'q' // set q
      obj.name = 'w' // set q
      console.log(obj.name); // get!   w

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      var obj = {
        name: 'rio',
        age: 20,
        no: 256
      }

      Object.defineProperties(obj,{
        name:{
          configurable:true
        },
        age:{
          configurable: true
        }
      })

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      var obj = {
        name: 'rio',
        age: 20,
        no: 256
      }

      console.log(Object.getOwnPropertyDescriptor(obj,'name'));
      console.log(Object.getOwnPropertyDescriptors(obj));

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  let name = 'rio'
  let age = 20
  let key = 'qwe'

  let obj = {
    name,
    age,
    [key]: "zxc"
  }

  console.log(obj);  // {name: 'rio', age: 20, qwe: 'zxc'}
  let {name:a,age:b=25,qwe:c,d=25} = obj
  console.log(a,b,c,d);  // rio 20 zxc 25

  let {name:a,...b} = obj
  console.log(a,b);  // rio {age: 20, qwe: 'zxc'}

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Rio的个人博客

Choose mode

对象扩展

#

# 属性描述符

# 数据属性描述符

# 遍历对象

# 存取属性描述符

# 多属性描述符

# 对象方法

# Object.getOwnPropertyDescriptor

# Object.preventExtensions

# Object.seal

# Object.freeze

# 字面量增强和解构

# 参考