JavaScriptのArray.includes()遅すぎぃぃ！【Array.includes() vs key in Object vs Set.has() vs Map.has()】

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TL;DR

V8に最適化なんて入ってなかった

セットアップ

const array = Array(1000000).fill().map(()=>Math.random().toString().slice(-8))
const object = Object.fromEntries(array.map(a => [a]))
const map = new Map(array.map(a => [a]))
const set = new Set(array)

Array.includes() 251 ops/s

array.includes(Math.random().toString().slice(-8))

Array.indexOf() 229 ops/s

array.indexOf(Math.random().toString().slice(-8))

Object[key] 1,957,463 ops/s

object[Math.random().toString().slice(-8)]

Object.hasOwnProperty() 2,217,807 ops/s

object.hasOwnProperty(Math.random().toString().slice(-8))

key in Object 2,193,181 ops/s

Math.random().toString().slice(-8) in object

Map.has() 1,430,881 ops/s

map.has(Math.random().toString().slice(-8))

Set.has() 1,783,334 ops/s

set.has(Math.random().toString().slice(-8))

for 205 ops/s

const target = Math.random().toString().slice(-8)
let exists = false
const length = array.length
for(var i = 0; i < length; i++) {
    if (array[i] === target) {
        exists = true
        break
    }
}

Node.js

key in Objectが最速っぽい？

array.includes(Math.random().toString().slice(-8)) 255.31212026521055
array.indexOf(Math.random().toString().slice(-8)) 273.96164583508994
object[Math.random().toString().slice(-8)] 1377596.804375387
object.hasOwnProperty(Math.random().toString().slice(-8)) 1686838.1590012764
Math.random().toString().slice(-8) in object 1750538.4657379298
map.has(Math.random().toString().slice(-8)) 1347472.81481226
set.has(Math.random().toString().slice(-8)) 1391667.3915078628

const array = Array(1000000).fill().map(() => Math.random().toString().slice(-8))
const object = Object.fromEntries(array.map(a => [a]))
const map = new Map(array.map(a => [a]))
const set = new Set(array)

const functions = [
    () => array.includes(Math.random().toString().slice(-8)),
    () => array.indexOf(Math.random().toString().slice(-8)),
    () => object[Math.random().toString().slice(-8)],
    () => object.hasOwnProperty(Math.random().toString().slice(-8)),
    () => Math.random().toString().slice(-8) in object,
    () => map.has(Math.random().toString().slice(-8)),
    () => set.has(Math.random().toString().slice(-8)),
]

for (const func of functions) {
    const iters = 10000
    const now = performance.now()
    Array(iters).fill().forEach(func)
    console.log(func.toString().slice(6), iters / (performance.now() - now) * 1000)
}

Google Cloud Shell

AWS Lambda

START RequestId: 27e4dd98-6b69-471f-93c6-18b8e7c60a9b Version: $LATEST
2023-02-24T00:19:42.323Z	27e4dd98-6b69-471f-93c6-18b8e7c60a9b	INFO	array.includes(Math.random().toString().slice(-8)) 100.11041055746443
2023-02-24T00:21:09.727Z	27e4dd98-6b69-471f-93c6-18b8e7c60a9b	INFO	array.indexOf(Math.random().toString().slice(-8)) 114.41227075738253
2023-02-24T00:21:09.738Z	27e4dd98-6b69-471f-93c6-18b8e7c60a9b	INFO	object[Math.random().toString().slice(-8)] 956500.0058246729
2023-02-24T00:21:09.748Z	27e4dd98-6b69-471f-93c6-18b8e7c60a9b	INFO	object.hasOwnProperty(Math.random().toString().slice(-8)) 1057379.8824432148
2023-02-24T00:21:09.757Z	27e4dd98-6b69-471f-93c6-18b8e7c60a9b	INFO	Math.random().toString().slice(-8) in object 1051999.1613521294
2023-02-24T00:21:09.770Z	27e4dd98-6b69-471f-93c6-18b8e7c60a9b	INFO	map.has(Math.random().toString().slice(-8)) 840604.0681615262
2023-02-24T00:21:09.781Z	27e4dd98-6b69-471f-93c6-18b8e7c60a9b	INFO	set.has(Math.random().toString().slice(-8)) 885716.8416465283
END RequestId: 27e4dd98-6b69-471f-93c6-18b8e7c60a9b
REPORT RequestId: 27e4dd98-6b69-471f-93c6-18b8e7c60a9b	Duration: 189717.39 ms	Billed Duration: 189718 ms	Memory Size: 10240 MB	Max Memory Used: 517 MB	Init Duration: 212.71 ms	

まとめ

• 要素数が少ないなら、Array.includes(key)
• 短く書きたいなら、key in Object
• notもつけたいなら !object.hasOwnProperty(key)