Compare the throughput of Array.forEach and Array.map

forEach_vs_map.js

const { performance } = require('perf_hooks');
const times = 1000;

const formatter = (num) => Math.floor(num * 100) / 100;

const benchmark = (fn) => {
  performance.mark('A');
  fn.call()
  performance.mark('B');
  performance.measure('A to B', 'A', 'B');
  const measure = performance.getEntriesByName('A to B')[0];
  performance.clearMeasures();
  return measure.duration;
};

const benchmarks = (fn) => {
  let min = 999, max = 0, sum = 0;
  Array(times).fill(0).map(() => benchmark(fn)).map((ms) => {
    sum += ms;
    max = (max < ms) ? ms : max;
    min = (min > ms) ? ms : min;
  });
  console.log(`max = ${formatter(max)}ms : min = ${formatter(min)}ms : ave = ${formatter(sum / times)}ms`);
};

const arr1 = Array(1000000).fill(1);

console.log('forEach');
benchmarks(() => {
  const arr2 = [];
  arr1.forEach((elem) => {
    arr2.push(`${elem} hoge`);
  });
});

console.log();
console.log('map');
benchmarks(() => {
  const arr2 = arr1.map((elem) => {`${elem} hoge`});
});