JSFiddle - React, Tailwind, and code Playground

JavaScript

const x = [1,3,7,4,9];
const y = [2,3,9,13,4];

const yFilteredByX = y.filter(element => x.includes(element));
const xFilteredByY = x.filter(element => y.includes(element));

const unique = (value, index, self) => {
return self.indexOf(value) === index;
};

const newArr = yFilteredByX.concat(xFilteredByY);
const uniqueArr = newArr.filter(unique);

console.log(uniqueArr);