1. 오름차순 정렬

let arr = [20, 40, 10, 50, 30];

arr.sort((a, b) => a - b);  // [10, 20, 30, 40, 50]

2. 내림차순 정렬

let arr = [20, 40, 10, 50, 30];

arr.sort((a, b) => b - a);  // [50, 40, 30, 20, 10]