es8对象方法扩展 Object.keys Object.values Object.entries Object.getOwnPropertyDescriptors

 

     const school = {

       name:"中国",

       cityies:["北京","上海","深圳"],

       area:["朝阳区","黄埔","东城"]

     }

     // 获取对象所有的键

    //  console.log(Object.keys(school)); //  (3) ["name", "cityies", "area"]

    // 获取 所有的 值

    // console.log(Object.values(school));  // ["中国", Array(3), Array(3)]

    // entries 返回一个数组 0 键=> 1值

    // console.log(Object.entries(school));  // [Array(2), Array(2), Array(2)]

    // 创建 Map

    // const m =new Map(Object.entries(school));

    // console.log(m); // {"name" => "中国", "cityies" => Array(3), "area" => Array(3)}

    // console.log(m.get('name'));  // 中国

    // 对象属性的 描述对象

    // console.log(Object.getOwnPropertyDescriptors(school));

    const obj = Object.create(null,{

      name:{

        value:'Eric',

        writable:true,

        configurable:true,

        enumerable: true

      }

    })

    console.log(obj); // {name: "Eric"}