使用Set求两个数组的并集|| 交集||差集

let a = new Set([1, 2, 3]);
let b = new Set([4, 3, 2]);

并集

let union = new Set([...a, ...b]);
// Set {1, 2, 3, 4}

交集

let intersect = new Set([...a].filter(x => b.has(x)));
// set {2, 3}

差集

let difference = new Set([...a].filter(x => !b.has(x)));
// Set {1}