Types of map key and object key

    // Map Type of key ： One  Map The bond of can be any value , Include function 、 Object or any basic type .
    // Object Type of key ： One Object  The key of must be a  String  or Symbol.
    var map = new Map();
    map.set(function test() {}, 123);
    map.set('name', ' Zhang San ');
    console.log(map);// {ƒ => 123, 'name' => ' Zhang San '}.“=>” Called Mapping 

    var obj = {
        age: 18,
        'address': 'js',
    }
    console.log(obj)// {age: 18, address: 'js'}. Object key:value

Reference resources MDN：https://developer.mozilla.org...