Run results for: reduce with object spread vs foreach with adding

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.110 Safari/537.36

Browser: Chrome 70

Operating system: Mac OS X 10.12.6

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
Using reduce and the spread operator	143272.7 Ops/sec
Using map and adding to an object	1700154.0 Ops/sec

Tests:

Using reduce and the spread operator
const styles = { foo: { color: 'red', }, bar: { color: 'green', '&:focus': { color: 'blue', }, }, foo2: { color: 'red', }, bar2: { color: 'green', '&:focus': { color: 'blue', }, }, foo3: { color: 'red', }, bar3: { color: 'green', '&:focus': { color: 'blue', }, }, foo4: { color: 'red', }, bar4: { color: 'green', '&:focus': { color: 'blue', }, }, }; Object .keys(styles) .reduce((classes, selector) => ({ ...classes, [selector]: selector, }), {});
Using map and adding to an object
const styles = { foo: { color: 'red', }, bar: { color: 'green', '&:focus': { color: 'blue', }, }, foo2: { color: 'red', }, bar2: { color: 'green', '&:focus': { color: 'blue', }, }, foo3: { color: 'red', }, bar3: { color: 'green', '&:focus': { color: 'blue', }, }, foo4: { color: 'red', }, bar4: { color: 'green', '&:focus': { color: 'blue', }, }, }; const obj = {}; Object .keys(styles) .forEach(style => { obj[style] = style; })