how to match 2 arrays in javascript code example

Example 1: javascript compare arrays

Array.prototype.equals = function(arr2) {
  return (
    this.length === arr2.length &&
    this.every((value, index) => value === arr2[index])
  );
};

[1, 2, 3].equals([1, 2, 3]);	// true
[1, 2, 3].equals([3, 6, 4, 2]);	// false

Example 2: javascript find matching elements in two arrays

let firstArray = ["One", "Two", "Three", "Four", "Five"];
let secondArray = ["Three", "Four"];

let map = {};
firstArray.forEach(i => map[i] = false);
secondArray.forEach(i => map[i] === false && (map[i] = true));
let jsonArray = Object.keys(map).map(k => ({ name: k, matched: map[k] }));