Run results for: for(const item of array) vs. for(const [k, v] of Object.entries(object))

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:138.0) Gecko/20100101 Firefox/138.0

Browser: Firefox 138

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

for(const item of array)

15.3M/s

for(const [k, v] of Object.entries(object))

3.2M/s

View exact numbers

Test name	Executions per second
✓ for(const item of array)	15,308,425 Ops/sec
for(const [k, v] of Object.entries(object))	3,188,438 Ops/sec

Script Preparation code:

const ARRAY  = [{ key: 'a', foo: 'bar' }, { key: 'b', foo: 'bar' }, { key: 'c', foo: 'bar' }, { key: 'd', foo: 'bar' }];
const OBJECT = {'a': { foo: 'bar' }, 'b': { foo: 'bar' }, 'c': { foo: 'bar' }, 'd': { foo: 'bar' }};

Tests:

for(const item of array)
for(const item of ARRAY) { const test = true; }
for(const [k, v] of Object.entries(object))
for(const [k, v] of Object.entries(OBJECT)) { const test = true; }