Benchmark: for key in object iteration vs for of array iteration

for key in object iteration vs for of array iteration (version: 2)

Comparing performance of: `Obj key for in iteration vs Array key for of iteration vs Obj key precreate keys for of iteration vs Array tuple for of iteration vs Precomputed obj keys iterative obj key access vs Array tuple stack pop vs Array tuple for index iteration`

Created: one year ago by: Registered User

Go to the latest result

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

const obj = {};
const array = [];
const arrayTuples = [];

let expectedSum = 0;
for (let i = 0; i < 1000; i++){
	const letterNum1 = i % 27;
  	const letterNum2 = i % 5;
  	const letterNum3 = i % 13;
  	const key = String.fromCharCode(letterNum1 + 65, letterNum2 + 65, letterNum3 + 65)
    
    obj[key] = i;
    array.push(key);
	arrayTuples.push([key, i])
    
    expectedSum += i;
}
const preComputedKeys = Object.keys(obj);

Tests:

Obj key for in iteration
const arrayPop = [].concat(arrayTuples); let number = 0; for (const key in obj){ number += obj[key]; } return number === expectedSum
Array key for of iteration
const arrayPop = [].concat(arrayTuples); let number = 0; for (const key of array){ number += obj[key]; } return number === expectedSum
Obj key precreate keys for of iteration
const arrayPop = [].concat(arrayTuples); const keys = Object.keys(obj); let number = 0; for (const key of keys){ number += obj[key]; } return number === expectedSum
Array tuple for of iteration
const arrayPop = [].concat(arrayTuples); let number = 0; for (const tuple of arrayTuples){ number += tuple[1]; } return number === expectedSum
Precomputed obj keys iterative obj key access
const arrayPop = [].concat(arrayTuples); let number = 0; for (const key of preComputedKeys){ number += obj[key]; } return number === expectedSum
Array tuple stack pop
// I think calling pop removes items for following test runs // --> appears too fast without cloning the array const arrayPop = [].concat(arrayTuples); let number = 0; while (arrayPop.length > 0){ const item = arrayPop.pop(); number += item[1]; } return number === expectedSum
Array tuple for index iteration
const arrayPop = [].concat(arrayTuples); let number = 0; for (let i = 0; i < arrayTuples.length; i++){ number += arrayTuples[i][1]; } return number === expectedSum

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Obj key for in iteration
Array key for of iteration
Obj key precreate keys for of iteration
Array tuple for of iteration
Precomputed obj keys iterative obj key access
Array tuple stack pop
Array tuple for index iteration

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36

Browser/OS: Chrome 136 on Linux

View result in a separate tab

Array tuple for of iteration

576K/s

Array tuple stack pop

321K/s

Array tuple for index iteration

268K/s

Array key for of iteration

89K/s

Precomputed obj keys iterative obj key access

89K/s

Obj key precreate keys for of iteration

16K/s

Obj key for in iteration

13K/s

View exact numbers

Test name	Executions per second
✓ Array tuple for of iteration	576,243 Ops/sec
Array tuple stack pop	320,708 Ops/sec
Array tuple for index iteration	267,524 Ops/sec
Array key for of iteration	89,415 Ops/sec
Precomputed obj keys iterative obj key access	89,040 Ops/sec
Obj key precreate keys for of iteration	15,638 Ops/sec
Obj key for in iteration	13,380 Ops/sec