Run results for: reduce with object spread vs foreach with adding vs reduce without spread

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.80 Safari/537.36

Browser: Chrome 71

Operating system: Linux

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
Using reduce and the spread operator	390026.8 Ops/sec
Using map and adding to an object	1568088.0 Ops/sec
Using reduce without spread operator	1644045.0 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; })
Using reduce without 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; return classes; }, {});