Run results for: FlatMap method vs for loop

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/114.0

Browser: Firefox 114

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
flatMap	3554.9 Ops/sec
for loop	18449.4 Ops/sec

Script Preparation code:

var arr = Array(10_000).fill(0);

Tests:

flatMap
arr.flatMap(x => [x, x * 2]);
for loop
const n = arr.length; const acc = new Array(n * 2); for (let i = 0; i < n; i++){ const x = arr[i]; acc[i * 2] = x; acc[i * 2 + 1] = x * 2; }