const map = new Map([['b','666']]);
map.set('a', 555);
map.set(['a'],555);
console.log(map); //Map(3) {"b" => "666", "a" => 555, ["a"] => 555}
console.log(map.get('a'));// 555
console.log(map.get(['a'])); //undefind
map set数组对象时，其引用和get时不是同一个，内存地址不用，无法get(['a'])
