1. arguments 对象转成数组

  var argArray = Array.prototype.slice.call(arguments);

2. 数组求和

var numbers = [3, 5, 7, 2];
var sum = numbers.reduce((x, y) => x + y);
console.log(sum); // 17

3. 数组元素随机排序

console.log(list.sort(function() {
    return Math.random() - 0.5
})); 

4. 数组去重

const my_array = [1, 2, 2, 3, 3, 4, 5, 5]
const unique_array = [...new Set(my_array)];
console.log(unique_array); // [1, 2, 3, 4, 5]