Run results for: Separate filter vs filter inside forEach

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:98.0) Gecko/20100101 Firefox/98.0

Browser: Firefox 98

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Just loop and simpleFilter inside	92.0 Ops/sec
Just loop and advancedFilter inside	37.0 Ops/sec
simpleFilter and loop	59.2 Ops/sec
advancedFilter and loop	18.9 Ops/sec

Script Preparation code:

var arr = [];
for (let i = 0; i < 1000000; ++i) {
    arr[i] = Math.floor(Math.random() * 1000)
}

function simpleFilter(i) {
    return i % 2 == 0
}

function advancedFilter(i) {
    return Math.round(i * 235.78) % 6 < 2
        || Math.round(i * 8945.78) % 7 < 3
        && Math.round(Math.sqrt(i)) * Math.round(Math.sqrt(i)) == i
}

var counters = {
    "t1a": 0,
    "t1b": 0,
    "t2a": 0,
    "t2b": 0,
}

Tests:

Just loop and simpleFilter inside
arr.forEach(i => { if (i % 2 == 0) { ++counters["t1a"] } })
Just loop and advancedFilter inside
arr.forEach(n => { if (Math.round(i * 235.78) % 6 < 2 || Math.round(i * 8945.78) % 7 < 3 && Math.round(Math.sqrt(i)) * Math.round(Math.sqrt(i)) == i) { ++counters["t1b"] } })
simpleFilter and loop
arr.filter(i => simpleFilter(i)).forEach(_ => ++counters["t2a"])
advancedFilter and loop
arr.filter(i => advancedFilter(i)).forEach(_ => ++counters["t2b"])

Run results for: Separate filter vs filter inside forEach

Just loop and simpleFilter inside

Just loop and advancedFilter inside

simpleFilter and loop

advancedFilter and loop