Run results for: for key in object iteration vs for of array iteration

Run details:

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

Browser: Chrome 136

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

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

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