1、数组去重
[...new Set([5,1,2,3,2,3,4,3,2,1])]得到[5, 1, 2, 3, 4]
2、展平多维数组
[].concat(...[1,[2,3],4,[5,6,7],8,9])得到[1, 2, 3, 4, 5, 6, 7, 8, 9]
3、随机排列数组中的元素
let arr = [1, 2, 3, 4, 5, 6, 7, 8, 9];arr.sort(() => Math.random()-0.5);

变量做属性名let my_name = 'abc';let my_obj = {[my_name]:'i am val'}即{abc: "i am val"}

剩余运算符let [a,...b]=[11,22,33];解构结果：a为11，b为[22,33]