Benchmark: Instanceof vs string comparison vs property checking vs constructor comparison

Instanceof vs string comparison vs property checking vs constructor comparison (version: 5)

Measure the performance of instanceOf operator vs comparing a basic string type.

Comparing performance of: instanceof Promise (promise) vs instanceof Promise (empty object) vs instanceof Promise (null) vs then check (promise) vs then check (empty object) vs then check (null) vs constructor comparison (promise) vs constructor comparison (empty object) vs constructor comparison (null) vs type obj?.then === function (promise) vs type obj?.then === function (empty object) vs type obj?.then === function (null) vs then in (promise) vs then in (empty object) vs then in (null) vs instanceof Promise (undefined) vs then check (undefined) vs constructor comparison (undefined) vs type obj?.then === function (undefined) vs then in (undefined)

Created: one year ago by: Registered User

Go to the latest result

Script Preparation code:

const obj = new Promise(() => {});
const obj2 = {};
const obj3 = null;
const obj4 = undefined;

Tests:

instanceof Promise (promise)
obj instanceof Promise
instanceof Promise (empty object)
obj2 instanceof Promise
instanceof Promise (null)
obj3 instanceof Promise
then check (promise)
obj?.then
then check (empty object)
obj2?.then
then check (null)
obj3?.then
constructor comparison (promise)
obj?.constructor === Promise
constructor comparison (empty object)
obj2?.constructor === Promise
constructor comparison (null)
obj3?.constructor === Promise
type obj?.then === function (promise)
typeof obj?.then === 'function'
type obj?.then === function (empty object)
typeof obj2?.then === 'function'
type obj?.then === function (null)
typeof obj3?.then === 'function'
then in (promise)
obj && 'then' in obj
then in (empty object)
obj2 && 'then' in obj2
then in (null)
obj3 && 'then' in obj3
instanceof Promise (undefined)
obj instanceof Promise
then check (undefined)
obj4?.then
constructor comparison (undefined)
obj4?.constructor === Promise
type obj?.then === function (undefined)
typeof obj4?.then === 'function'
then in (undefined)
obj4 && 'then' in obj4

Historical Performance Data aggregated from 9 community runs

Desktop Results:

Chrome 9 runs

instanceof Promise (null)

281.3M/s

instanceof Promise (promise)

279.1M/s

then in (promise)

277.0M/s

constructor comparison (promise)

274.7M/s

then check (promise)

272.0M/s

type obj?.then === function (null)

270.8M/s

type obj?.then === function (promise)

270.1M/s

constructor comparison (null)

270.0M/s

then in (null)

269.4M/s

then check (null)

268.4M/s

constructor comparison (empty object)

259.4M/s

type obj?.then === function (empty object)

257.4M/s

then in (empty object)

255.9M/s

then check (empty object)

255.5M/s

instanceof Promise (empty object)

223.7M/s

Fastest: instanceof Promise (null) (1.3x faster)

View exact numbers

✓ instanceof Promise (null): 281,329,920 ops/sec
• instanceof Promise (promise): 279,110,336 ops/sec
• then in (promise): 277,024,768 ops/sec
• constructor comparison (promise): 274,690,304 ops/sec
• then check (promise): 272,032,704 ops/sec
• type obj?.then === function (null): 270,843,008 ops/sec
• type obj?.then === function (promise): 270,145,664 ops/sec
• constructor comparison (null): 270,014,592 ops/sec
• then in (null): 269,355,904 ops/sec
• then check (null): 268,432,352 ops/sec
• constructor comparison (empty object): 259,397,024 ops/sec
• type obj?.then === function (empty object): 257,449,760 ops/sec
• then in (empty object): 255,866,288 ops/sec
• then check (empty object): 255,511,488 ops/sec
• instanceof Promise (empty object): 223,709,696 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
instanceof Promise (promise)
instanceof Promise (empty object)
instanceof Promise (null)
then check (promise)
then check (empty object)
then check (null)
constructor comparison (promise)
constructor comparison (empty object)
constructor comparison (null)
type obj?.then === function (promise)
type obj?.then === function (empty object)
type obj?.then === function (null)
then in (promise)
then in (empty object)
then in (null)
instanceof Promise (undefined)
then check (undefined)
constructor comparison (undefined)
type obj?.then === function (undefined)
then in (undefined)

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36

Browser/OS: Chrome 136 on Mac OS X 10.15.7

View result in a separate tab

instanceof Promise (promise)

303.8M/s

then check (promise)

298.3M/s

instanceof Promise (null)

290.1M/s

then in (null)

285.5M/s

constructor comparison (promise)

277.4M/s

then in (promise)

277.1M/s

constructor comparison (null)

273.1M/s

type obj?.then === function (promise)

269.3M/s

then check (null)

265.4M/s

then in (empty object)

262.3M/s

constructor comparison (empty object)

260.7M/s

type obj?.then === function (null)

260.6M/s

type obj?.then === function (empty object)

257.4M/s

then check (empty object)

254.2M/s

instanceof Promise (empty object)

241.7M/s

View exact numbers

Test name	Executions per second
✓ instanceof Promise (promise)	303,837,824 Ops/sec
then check (promise)	298,302,976 Ops/sec
instanceof Promise (null)	290,129,280 Ops/sec
then in (null)	285,495,616 Ops/sec
constructor comparison (promise)	277,396,320 Ops/sec
then in (promise)	277,073,248 Ops/sec
constructor comparison (null)	273,117,664 Ops/sec
type obj?.then === function (promise)	269,327,680 Ops/sec
then check (null)	265,423,008 Ops/sec
then in (empty object)	262,307,344 Ops/sec
constructor comparison (empty object)	260,667,152 Ops/sec
type obj?.then === function (null)	260,597,456 Ops/sec
type obj?.then === function (empty object)	257,449,760 Ops/sec
then check (empty object)	254,150,944 Ops/sec
instanceof Promise (empty object)	241,658,960 Ops/sec

Instanceof vs string comparison vs property checking vs constructor comparison (version: 5)

Measure the performance of instanceOf operator vs comparing a basic string type.

Created: one year ago by: Registered User

Go to the latest result

instanceof Promise (promise)

instanceof Promise (empty object)

instanceof Promise (null)

then check (promise)

then check (empty object)

then check (null)

constructor comparison (promise)

constructor comparison (empty object)

constructor comparison (null)

type obj?.then === function (promise)

type obj?.then === function (empty object)

type obj?.then === function (null)

then in (promise)

then in (empty object)

then in (null)

instanceof Promise (undefined)

then check (undefined)

constructor comparison (undefined)

type obj?.then === function (undefined)

then in (undefined)

Historical Performance Data aggregated from 9 community runs

Desktop Results:

Chrome 9 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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