更简单的求合集、交集和并集

Question

就是最简单的数学题：求两个数组的合集、交集和并集。我知道可以用for循环，但有没有更加简单的方法？var arr1 = [3, 5, 1];var arr2 = [2, 5, 7];......

Answer 1

let arr1 = [2, 3, 5, 10];

let arr2 = [1, 3, 7, 10];

console.log( '并集', [...new Set([...arr1, ...arr2])] ); // [2, 3, 5, 10, 1, 7]

console.log( '交集', arr1.filter(a => (arr2.indexOf(a) !== -1)) ); // [3, 10]

console.log( '差集', arr1.filter(a => (arr2.indexOf(a) === -1)) ); // [2, 5]