集合（并集 交集 差集）

并集

let s01 = [1, 2, 3, 1, 2, 6];
let s02 = [3, 4, 5, 1, 2];
let s1 = new Set(s01); //去重
let s2 = new Set(s02); //去重
let union = [...new Set([...s1, ...s2])];
console.log(union);   // [1, 2, 3, 6, 4, 5]

交集

let s01 = [1, 2, 3, 1, 2, 6];
let s02 = [3, 4, 5, 1, 2];
let intersection = [...new Set(s01)].filter(item => new Set(s02).has(item));
console.log(intersection);    //[1, 2, 3]

差集

let s01 = [1, 2, 3, 1, 2, 6];
let s02 = [3, 4, 5, 1, 2];
let diff = [...new Set(s01)].filter(item => !new Set(s02).has(item));
console.log(diff);//6