交集

let arr1 = [1, 2, 3, 4]
let arr2 = [2, 3, 4, 5, 6]
let s1 = new Set(arr1)
let s2 = new Set(arr2)
let result = new Set(arr1.filter(item => s2.has(item)))
console.log(Array.from(result)) // [ 2, 3, 4 ]

并集

let arr1 = [1, 2, 3, 4];
let arr2 = [2, 3, 4, 5, 6];
let s1 = new Set([1, 2, 3, 4])
let s2 = new Set([2, 3, 4, 5, 6])
console.log([...s1, ...s2])
console.log(new Set([...arr1, ...arr2]))

差集

let arr1 = [1, 2, 3, 4];
let arr2 = [2, 3, 4, 5, 6];
let s1 = new Set([1, 2, 3, 4])
let s2 = new Set([2, 3, 4, 5, 6])
let arr3 = new Set(arr1.filter(item => !s2.has(item)))
let arr4 = new Set(arr2.filter(item => !s1.has(item)))
console.log(arr3) // Set(1) { 1 }
console.log(arr4) // Set(2) { 5, 6 }  
console.log([...arr3, ...arr4]) // [ 1, 5, 6 ]