Benchmark: JavaScript Object.assign vs for in loop vs for of loop vs Object.entries

Tests:

Object.assign
const a = { x: 'xxx', y: 1, z: null } const b = { z: 1, u: 'uuu', v: null } Object.assign(a, b);
for in loop
const a = { x: 'xxx', y: 1, z: null } const b = { z: 1, u: 'uuu', v: null } for (const prop in b) { if (b.hasOwnProperty(prop)) { a[prop] = b[prop]; } }
for of loop
const a = { x: 'xxx', y: 1, z: null } const b = { z: 1, u: 'uuu', v: null } for (const prop of Object.keys(b)) { a[prop] = b[prop]; }
for Object entries
const a = { x: 'xxx', y: 1, z: null } const b = { z: 1, u: 'uuu', v: null } for (const [key, value] of Object.entries(b)) { a[key] = value; }
for in without check
const a = { x: 'xxx', y: 1, z: null } const b = { z: 1, u: 'uuu', v: null } for (const prop in b) { a[prop] = b[prop]; }

Rendered benchmark preparation results:

Previous results

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Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/111.0

Browser/OS: Firefox 111 on Mac OS X 10.15

JavaScript Object.assign vs for in loop vs for of loop vs Object.entries (version: 0)