ES6数组去重

使用ES6的新语法对数组去重，相比ES5省去了排序再做双重For循环

(function() {    'use strict';    let arr = [1, '1', 2, '2', 3, '3', 3, '3', 2, '2', 1, '1'];    let new_set =  new Set(arr);    let new_arr = Array.from(new_set);    console.log(new_arr);})();