代碼快速查 —— ES6

數組去重：

let arr = [3, 5, 2, 2, 5, 5];

let unique = [...new Set(arr)];

並、交、差集

let a = new Set([1, 2, 3]);

let b = new Set([4, 3, 2]);

1. 並集：let unique = new Set([...a, ...b]);
2. 交集：let intersect = new Set([...a]).filter(x => b.has(x));
3. 差集：let diffrence = new Set([...a]).filter(x => !b.has(x)); // 這裏是一種左差a-b，還有一種右差b-a，自行修改即可