Examples of Set Theory from https://medium.com/@alvaro.saburido/set-theory-for-arrays-in-es6-eb2f20a61848

setTheory.js

// Examples of https://medium.com/@alvaro.saburido/set-theory-for-arrays-in-es6-eb2f20a61848
const arrA = [1, 3, 4, 5];
const arrB = [1, 2, 5, 6, 7];

const intersection = arrA.filter((x) => arrB.includes(x));
console.log('Intersection: ', intersection);
console.log('Expected: [1,5]');

const difference = arrA.filter((x) => !arrB.includes(x));
console.log('\nDifference: ', difference);
console.log('Expected: [3,4]');

const symmetricalDifference = arrA
  .filter((x) => !arrB.includes(x))
  .concat(arrB.filter((x) => !arrA.includes(x)));
console.log('\nSymmetrical Difference: ', symmetricalDifference);
console.log('Expected: [2,3,4,6,7]');

const union = [...new Set([...arrA, ...arrB])];
console.log('\nUnion: ', union);
console.log('Expected: [1,2,3,4,5,6,7]');