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: 11 months ago by: Registered User

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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: 11 months 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

Test name	Executions per second
Obj key for in iteration	13380.0 Ops/sec
Array key for of iteration	89415.0 Ops/sec
Obj key precreate keys for of iteration	15638.0 Ops/sec
Array tuple for of iteration	576242.8 Ops/sec
Precomputed obj keys iterative obj key access	89040.1 Ops/sec
Array tuple stack pop	320708.2 Ops/sec
Array tuple for index iteration	267523.6 Ops/sec

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