Run results for: JavaScript Object.assign vs for in loop new

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/113.0.0.0 Safari/537.36

Browser: Chrome 113

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
Object.assign	3327468.2 Ops/sec
for in loop	5158178.5 Ops/sec

Tests:

Object.assign
const a = { A: 'a', B: 'b', C: 'c', D: 'd', E: 'e', F: 'f', G: 'g', H: 'h', I: 'i', J: 'j', K: 'k', L: 'l', M: 'm', } const b = { A: 'n', B: 'o', C: 'p', D: 'q', E: 'r', F: 's', G: 't', H: 'u', I: 'v', J: 'w', K: 'x', L: 'y', M: 'z', } Object.assign(a, b);
for in loop
const a = { A: 'a', B: 'b', C: 'c', D: 'd', E: 'e', F: 'f', G: 'g', H: 'h', I: 'i', J: 'j', K: 'k', L: 'l', M: 'm', } const b = { A: 'n', B: 'o', C: 'p', D: 'q', E: 'r', F: 's', G: 't', H: 'u', I: 'v', J: 'w', K: 'x', L: 'y', M: 'z', } for (let prop in b) a[prop] = b[prop];