Run results for: Object isEmpty: for-in vs Object.keys

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.6 Mobile/22G86 Safari/604.1

Browser: Mobile Safari 18

Operating system: iOS 18.6

Device Platform: Mobile

Date tested: 8 months ago

Test name	Executions per second
for-in	75942.3 Ops/sec
Object.keys	71076.9 Ops/sec
Object.values	71872.1 Ops/sec
for-in with isOwnProperty	61170.9 Ops/sec

Script Preparation code:

const numObjects = 25;
const fractionEmpty = 0.5;
var objs = Array.from({
    length: numObjects
}, () => {
    if (Math.random() < fractionEmpty) return {};
    const numKeys = 3 + Math.floor(Math.random() * 4);
    return Object.fromEntries(Array.from({
        length: numKeys
    }, (_, idx) => {
        return [idx, Math.random()];
    }));
});

Tests:

for-in
outerLoop: for (const obj of objs) { for (var key in obj) { console.log(true); continue outerLoop; } console.log(false); }
Object.keys
for (const obj of objs) { const isEmpty = Object.keys(obj).length === 0 console.log(isEmpty); }
Object.values
for (const obj of objs) { const isEmpty = Object.values(obj).length === 0 console.log(isEmpty); }
for-in with isOwnProperty
outerLoop: for (const obj of objs) { for (var key in obj) { if (Object.hasOwn(obj, key)) { console.log(true); continue outerLoop; } console.log(false); } console.log(false); }

Run results for: Object isEmpty: for-in vs Object.keys

Compares performance of using for-in vs Object.keys for checking emptiness of an object.

for-in

Object.keys

Object.values

for-in with isOwnProperty