Run results for: forIn vs forOf vs optimised forOf

Run details:

User agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.167 Safari/537.36

Browser: Chrome 64

Operating system: Windows 7

Device Platform: Other

Date tested: 2025 years ago

Script Preparation code:

//set up
var abc = new Object()
for(var intCtr=0; intCtr<1000; intCtr++) {
	abc[intCtr+''] = Math.floor(Math.random() * Math.floor(10000))
}

Tests:

for in
var forInResult = 0; for(var key in abc) { forInResult += abc[key] }
for of
var forOfResult = 0; for(var key of Object.keys(abc)) { forOfResult += abc[key] }
for of optimised
var forOfKeys = Object.keys(abc); var forOfKeysResult = 0; for(var key of forOfKeys) { forOfKeysResult += abc[key]; }