Run results for: test reduce with rest vs from entries vs reduce without new object2

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/107.0.0.0 Safari/537.36

Browser: Chrome 107

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
reduce with new object	9.0 Ops/sec
fromEntries	2573.3 Ops/sec
reduce without new object	4557.8 Ops/sec
forEach	6100.0 Ops/sec
for	3633.5 Ops/sec

Script Preparation code:

function generateTestData(size) {
  const testData = [];
  for (let i = 0; i < size; i++) {
    const key = `key_${i}`;
    const values = [];
    for (let j = 0; j < size; j++) {
      values.push(`value_${i}_${j}`);
    }
    testData.push({ key, values });
  }
  return testData;
}

var testData = generateTestData(1000);

Tests:

reduce with new object
const result = testData.reduce((res, { key, values }) => ({ ...res, [key]: values }), {});
fromEntries
const result = Object.fromEntries(testData.map(({ key, values }) => [key, values]));
reduce without new object
const result = testData.reduce((res, { key, values }) => { res[key] = values; return res; }, {});
forEach
const results = {} testData.forEach(({ key, values }) => { results[key] = values; });
for
const result = {}; for (let i = 0; i < testData.length; i++) { const { key, values } = testData[i]; result[key] = values; }

Run results for: test reduce with rest vs from entries vs reduce without new object2

reduce with new object

fromEntries

reduce without new object

forEach

for