Benchmarking append values to arrays

loop-append-array.js

const Benchmark = require('benchmark')

const suite = new Benchmark.Suite

const array = [];

for (let i = 0; i < 1000; i++) {
  array.push({ value: i });
}

suite
.add('foreach & push', () => {
  let res = [{ value: 1 }, { value: 2 }, { value: 3 }, { value: 4 }]
  array.forEach(item => {
    res.push({ value: item.value * 2 });
  });
})
.add('for (const of) & push', () => {
  let res = [{ value: 1 }, { value: 2 }, { value: 3 }, { value: 4 }]
  for (const item of array) {
    res.push({ value: item.value * 2 });
  }
})
.add('for (let i) & push', () => {
  let res = [{ value: 1 }, { value: 2 }, { value: 3 }, { value: 4 }]
  for (let i = 0; i < array.length; ++i) {
    const item = array[i];

    res.push({ value: item.value * 2 });
  }
})
.add('map & concat', () => {
  let res = [{ value: 1 }, { value: 2 }, { value: 3 }, { value: 4 }]
  let res2 = array.map(item => {
    return { value: item.value * 2 }
  });

  res = res.concat(res2)
})
.on('cycle', function(event) {
  console.log(String(event.target));
})
.on('complete', function() {
  console.log('Fastest is ' + this.filter('fastest').map('name'));
})
.run();

results.txt

$ node --version
v12.13.0
$ node loop-append-array.js
   foreach & push x 105,624 ops/sec ±2.96% (86 runs sampled)
   for (const of) & push x 112,869 ops/sec ±1.38% (87 runs sampled)
   for (let i) & push x 110,137 ops/sec ±1.68% (86 runs sampled)
   map & concat x 137,630 ops/sec ±1.49% (81 runs sampled)
 Fastest is map & concat