bench.js

// run with `matcha bench.js`

const cars = ['Tesla', 'Tata', 'Ford', 'Land Rover', 'Audi'];
let x;

bench('for-let', () => {
  for (let i = 0; i < cars.length; i++) {
    x = cars[i];
  }
});

bench('forEach', () => {
  cars.forEach(car => {
    x = car;
  });
});

bench('for of', () => {
  for (const car of cars) {
    x = car;
  }
});

bench('for in', () => {
  for (const car in cars) {
    x = car;
  }
});