Run results for: concat map

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36

Browser: Chrome 79

Operating system: Mac OS X 10.14.6

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
concat 1	515.3 Ops/sec
concat 2	6537.8 Ops/sec
concat 1 small to large	50563.7 Ops/sec
concat 2 small to large	41234.9 Ops/sec

Script Preparation code:

function concatMap1(xs, fn) {
    return xs.map(v => fn(v)).reduce((acc, arr) => Array.isArray(arr) ? acc.concat(arr) : acc.concat([arr]), []);
}

function concatMap2(xs, fn) {
    var res = [];
    for (var i = 0; i < xs.length; i++) {
        var x = fn(xs[i], i);
        if (Array.isArray(x)) res.push.apply(res, x);
        else res.push(x);
    }
    return res;
}

Tests:

concat 1
concatMap1(Array(1000).fill(0), v => [v-1, v, v+1])
concat 2
concatMap2(Array(1000).fill(0), v => [v-1, v, v+1])
concat 1 small to large
concatMap1([1, 2, 3, 4], v => Array(1000).fill(v))
concat 2 small to large
concatMap2([1, 2, 3, 4], v => Array(1000).fill(v))

Run results for: concat map

comparing concat map implementations

concat 1

concat 2

concat 1 small to large

concat 2 small to large