JSFiddle - React, Tailwind, and code Playground

JavaScript

var numbers = [ 1, 2, 3, 4, 5 ];
var letters = [ "a", "b", "c", "d", "e" ];

function comp(numbers, letter) {
  return numbers.filter(function (number) {
    return number % 2 === 0;
  }).map(function (number) {
    return letters.map(function (letter) {
      return number + letter;
    });
  }).reduce(function (p, c) {
    return p.concat(c);
  });
}

console.log(comp(numbers, letters))