js数组排序(+洗牌)

var arr = [{   //对象数组    num: 1,    t: '111'}, {    num: 5,    t: '555'}, {    num: 6,    t: '666'}, {    num: 3,    t: '333'}];   arr.sort(function(a, b) {    //return a.num - b.num;   //从小到大排    //return b.num - a.num;   //从大到小排    //return Math.random() - 0.5;   //数组洗牌});