Run results for: Custom flatten function VS Array.prototype.flat

Run details:

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:77.0) Gecko/20100101 Firefox/77.0

Browser: Firefox 77

Operating system: Ubuntu

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
Custom Flatten Function	945303.8 Ops/sec
Array.prototype.flat	9098897.0 Ops/sec

Script Preparation code:

function flatten(arr) {
	let i = 0;
	const len = arr.length;
	const result = [];
	let item;

	while (i < len) {
		item = Array.isArray(arr[i]) ? flatten(arr[i]) : [arr[i]];
		[].push.apply(result, item);
		i += 1;
	}

	return result;
}

Tests:

Custom Flatten Function
var params = [ "hello", true, 7 ]; var other = flatten([1, 2, params]);
Array.prototype.flat
var params = [ "hello", true, 7 ]; var other = [1, 2, params].flat()

Run results for: Custom flatten function VS Array.prototype.flat

Compare a custom flatten function with Array.prototype.flat

Custom Flatten Function

Array.prototype.flat