A small benchmark of for vs forEach

woop-woop.js

// run in terminal with: node woop-woop.js [arraySize = 1000000] [runs = 1]
// e.g. `node woop-woop.js 1000 2` runs the benchmark twice with thousand users.
const runs = parseInt(process.argv[3] || 1);
const arraySize = parseInt(process.argv[2] || 1000000);
let usersToGiveCoins = Array(arraySize).fill({username: 'Koala', coins: 0});

// simple benchmark function to wrap time + timeEnd and
// allows running benchmark an arbitrary number of times.
function bench(label, fn, times = 1) {
    for (let i = 0; i < times; i++) {
        console.time(`${label}#${i + 1}`);
        fn();
        console.timeEnd(`${label}#${i + 1}`);
    }
}

console.log(`arraySize: ${arraySize}, runs: ${runs}`);

bench('forLoop', () => {
    for (let i = 0; i < usersToGiveCoins.length; i++) {
        usersToGiveCoins[i].coins += 5;
    }
}, runs);

bench('forEach', () => usersToGiveCoins.forEach(user => user.coins += 5), runs);