对象方法扩展 Object.is Object.assign Object.setPrototypeOf 设置原型对象 Object.getPrototypeOf 获取原型对象

   // 1 Object.is 判断两个值是否完全相等

    // console.log(Object.is(120,121)); // false

    // console.log(Object.is(120,120)); // true

    // console.log(Object.is(NaN,NaN)); // true

    // 2 Object.assign 对象的合并

    // const config1 = {

    //   host:'localhost',

    //   port:3306,

    //   name:'root',

    //   pass:'root',

    //   test:'test'

    // }

    // const config2 = {

    //   host:'http://127.0.0.1',

    //   port:33060,

    //   name:'Eric',

    //   pass:'IloveU',

    //   test2:'test2'

    // }

    // // 后面会把前面的给覆盖

    // let res = Object.assign(config1,config2); 

    // console.log(res);

    // 3 Object.setPrototypeOf 设置原型对象 Object.getPrototypeOf 获取原型对象

    const city = {

      name:'北京'

    };

    const area = {

      xiaoqu: ['朝阳','海淀','昌平']

    };

    // 设置原型对象

    Object.setPrototypeOf(city,area);

    console.log(city);

    // 获取原型对象

    console.log(Object.getPrototypeOf(city));