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

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36

Browser: Chrome 128

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

for-in

9K/s

Object.keys

9K/s

Object.values

9K/s

for-in with isOwnProperty

8K/s

View exact numbers

Test name	Executions per second
✓ for-in	8,781 Ops/sec
Object.keys	8,732 Ops/sec
Object.values	8,655 Ops/sec
for-in with isOwnProperty	8,147 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