Run results for: Object assign vs direct assignment by iterating keys and assigning

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36

Browser: Chrome 104

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
With Object.assign()	1917900.0 Ops/sec
With Iteration and Assignment	3489972.0 Ops/sec
With Iteration and .keys().forEach	2924347.0 Ops/sec

Tests:

With Object.assign()
var toSave = { "def":100101102, "ghi":null, "jkl":106107108, "mno":109110111.106107108, "pqr":'112113114', "stu":NaN, "vwx":118119120, "yz{":[ { "vwx":118119120 }, { "vwx":118119120 } ], }; var dest = { "abc":979899 }; if (toSave) { Object.assign(dest, toSave); }
With Iteration and Assignment
var toSave = { "def":100101102, "ghi":null, "jkl":106107108, "mno":109110111.106107108, "pqr":'112113114', "stu":NaN, "vwx":118119120, "yz{":[ { "vwx":118119120 }, { "vwx":118119120 } ], }; var dest = { "abc":979899 }; if (toSave) { var keys = Object.keys(dest); for (var i = 0; i < keys.length; i++) { dest[keys[i]] = toSave[keys[i]]; } }
With Iteration and .keys().forEach
var toSave = { "def":100101102, "ghi":null, "jkl":106107108, "mno":109110111.106107108, "pqr":'112113114', "stu":NaN, "vwx":118119120, "yz{":[ { "vwx":118119120 }, { "vwx":118119120 } ], }; var dest = { "abc":979899 }; if (toSave) { var keys = Object.keys(dest).forEach(key => { dest[key] = toSave[key]; }); }