Run results for: Performance of JavaScript .forEach, for in

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36

Browser: Chrome 109

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
.forEach	1.6 Ops/sec
for..of	1.9 Ops/sec

Script Preparation code:

function generateTestArray() {
  const result = [];
  for (let i = 0; i < 1000000; ++i) {
    result.push({
      a: i,
      b: i / 2,
      r: 0,
    });
  }
  return result;
}

AخA
 
function generateTestArray() {  const result = [];  for (let i = 0; i < 1000000; ++i) {    result.push({      a: i,      b: i / 2,      r: 0,    });  }  return result;}

Tests:

.forEach

const array = generateTestArray();
const newMap = new Map();
array.forEach((x) => {
  newMap.set(x.a, x.b);
});
const foo = [...newMap.entries()];

 
const array = generateTestArray();const newMap = new Map();array.forEach((x) => {  newMap.set(x.a, x.b);});const foo = [...newMap.entries()];

for..of

const array = generateTestArray();
const newMap = new Map();
for(const x of array) {
    newMap.set(x.a, x.b);
}
const foo = [...newMap.entries()];

 
const array = generateTestArray();const newMap = new Map();for(const x of array) {    newMap.set(x.a, x.b);}const foo = [...newMap.entries()];