compare-last-index-of.js

import Benchmark from 'benchmark'

const suite = new Benchmark.Suite()
const re = new RegExp([...Array(1000)].map((_, i) => `/${i}()$`).join('|'))
const m = '/500'.match(re)

console.log(m.length)
console.log(m.indexOf(''))

const io = Array.prototype.indexOf
const lio = Array.prototype.lastIndexOf
suite
  .add('indexOf()', () => {
    return m.indexOf('', 1)
  })
  .add('lastIndexOf()', () => {
    return m.lastIndexOf('')
  })
  .add('lastIndexOf by for', () => {
    for (let i = m.length - 1; i > 0; i--) {
      if (m[i] === '') {
        return i
      }
    }
    return -1
  })
  .add('lastIndexOf by while', () => {
    let i = m.length
    while (i--) {
      if (m[i] === '') {
        return i
      }
    }
    return -1
  })
  .add('Array.prototype.indexOf.call', () => {
    io.call(m, '', 1)
  })
  .add('Array.prototype.lastIndexOf.call', () => {
    lio.call(m, '')
  })
  .on('cycle', (event) => {
    console.log(String(event.target))
  })
  .on('complete', function () {
    console.log(`Fastest is ${this.filter('fastest').map('name')}`)
  })
  .run({ async: true })

Node.js v16.14.0@c5.large

indexOf() x 525,422,544 ops/sec ±0.50% (92 runs sampled)
lastIndexOf() x 620,680 ops/sec ±0.05% (95 runs sampled)
lastIndexOf by for x 1,698,597 ops/sec ±0.03% (94 runs sampled)
lastIndexOf by while x 1,362,382 ops/sec ±0.19% (99 runs sampled)
Array.prototype.indexOf.call x 1,672,314 ops/sec ±0.02% (94 runs sampled)
Array.prototype.lastIndexOf.call x 620,908 ops/sec ±0.03% (98 runs sampled)
Fastest is indexOf()

Node.js v17.5.0@c5.large

indexOf() x 611,477,018 ops/sec ±0.45% (91 runs sampled)
lastIndexOf() x 569,973 ops/sec ±0.10% (93 runs sampled)
lastIndexOf by for x 1,692,906 ops/sec ±0.03% (95 runs sampled)
lastIndexOf by while x 1,361,383 ops/sec ±0.08% (98 runs sampled)
Array.prototype.indexOf.call x 3,195,108 ops/sec ±0.06% (98 runs sampled)
Array.prototype.lastIndexOf.call x 570,631 ops/sec ±0.02% (98 runs sampled)
Fastest is indexOf()

Node.js v18.0.0-pre@i9

indexOf() x 517,641,986 ops/sec ±1.03% (85 runs sampled)
lastIndexOf() x 621,281 ops/sec ±1.31% (91 runs sampled)
lastIndexOf by for x 1,834,048 ops/sec ±2.22% (88 runs sampled)
lastIndexOf by while x 1,451,324 ops/sec ±1.10% (90 runs sampled)
Array.prototype.indexOf.call x 1,065,097 ops/sec ±1.30% (89 runs sampled)
Array.prototype.lastIndexOf.call x 554,862 ops/sec ±3.16% (83 runs sampled)
Fastest is indexOf()