Run results for: `filter().length` vs. `reduce` vs. `for` (with Set)

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/117.0

Browser: Firefox 117

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
filter().length	6050885.0 Ops/sec
reduce	10713478.0 Ops/sec
for loop	5451322.5 Ops/sec

Script Preparation code:

var sample = new Set(Array(1000).fill(0).map((_, idx) => idx));
var selected = [10, 134, 245, 355, 489, 583, 682, 823, 2081, 3892, 4892, 5829, 6832];

Tests:

filter().length
var total = selected.filter(id => sample.has(id)).length;
reduce
var total = selected.reduce((total, id) => total + (sample.has(id) ? 1 : 0), 0);
for loop
var total = 0; for (const id of selected) { if (sample.has(id)) { total++; } }

Run results for: `filter().length` vs. `reduce` vs. `for` (with Set)

Compare `filter().length` vs `reduce` vs `for` loop for counting array elements that are present in another array.

filter().length

reduce

for loop