Run results for: Map vs Map vs Foreach vs for - MeasureThat.net

Run details:

User agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Browser: Chrome 56

Operating system: Windows 8.1

Device Platform: Other

Date tested: 7 years ago

Test name	Executions per second
Overwrite	7004.8 Ops/sec
Dont overwrite	5609.2 Ops/sec
forEach	52912.1 Ops/sec
copy	7108.5 Ops/sec

Website performance monitoring

Script Preparation code:

var a = new Array(1000);
for (let i = 0; i < a.length; i++) {
  a[i] = {};
}

Tests:

Overwrite
a = a.map((row) => { row.checked = true; return row; });
Dont overwrite
const b = a.map((row) => { row.checked = true; return row; });
forEach
a.forEach((row) => { row.checked = true; });
for
for(let i=0; i<a.length; i++) { a[i].checked = true; }