Run results for: Creating new property, 1

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.132 Safari/537.36

Browser: Chrome 80

Operating system: Linux

Device Platform: Desktop

Date tested: 4 years ago

Script Preparation code:

data = [];

for (let i = 0; i < 1000000; i++) {
  data[i] = {
    prop: '1'
  };
}

Tests:

For
for (let i = 0; i < data.length; i++) { data[i].newProp = '1'; }
Map
data.map((current) => { current.newProp = '1'; });
Reduce
data.reduce((accumulator, current) => { accumulator.push({ ...current, newProp: '1' }); return accumulator; }, []);
Foreach
data.forEach((current) => { current.newProp = '1'; });
For reversed
for (let i = data.length - 1; i >= 0; i--) { data[i].newProp = '1'; }
while
let i = 0; while (i !== data.length) { data[i].newProp = '1'; i++; }