并集:

const arr1 = [1, 2, 3, 2, 5];
const arr2 = [1, 4, 6, 8, 3];

// 将两个数组合并
const concatArr = [...arr1, ...arr2]; 

// 对数组去重
const set = new Set(concatArr);

const newArr = [...set]

 

交集：

const arr1 = [1, 2, 3, 2, 5];
const arr2 = [1, 4, 6, 8, 3];

const set1 = new Set(arr1);
const set2 = new Set(arr2);

const newArr = [...set1].filter(item => {
    return set2.has(item);
});

 

 

差集：

const arr1 = [1, 2, 3, 2, 5];
const arr2 = [1, 4, 6, 8, 3];

// 首先用ES6的set给数组去重：
const set1 = new Set(arr1);
const set2 = new Set(arr2);

// 然后分别取出set1中存在，set2中不存在 和 set2中存在，set1中不存在的值
const newArr1 = [...set1].filter((item) => {
    return !set2.has(item);
});
const newArr2 = [...set2].filter(item => {
    return !set1.has(item);
});

// 再将得到的两个新数组合并，就能得到差集了
const newArr = [...newArr1,...newArr2];