js 执行sum(9) 可以输出9,8,7,6,5,4,3,2,1const sum = n => [...new Array(n + 1).keys()].reverse().slice(0,n)sum(9) [9, 8, 7, 6, 5, 4, 3, 2, 1]sum(11) 2023-02-28JavaScript220