Run results for: reduce concat vs flat vs concat spread vs reduce spread

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser: Chrome 135

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Benchmark engine: Benchmark.js

concat(...)

807K/s

reduce + Array.prototype.concat

531K/s

reduce spread

37K/s

Array.prototype.flat

14K/s

View exact numbers

Test name	Executions per second
✓ concat(...)	807,355 Ops/sec
reduce + Array.prototype.concat	530,731 Ops/sec
reduce spread	37,290 Ops/sec
Array.prototype.flat	14,431 Ops/sec

Script Preparation code:

var params = [
    [1, 2],
    ["hello", true, 7],
    Array(10000).fill(4),
];

Tests:

reduce + Array.prototype.concat
const x = params.reduce((acc, val) => acc.concat(val), []);
Array.prototype.flat
const x = params.flat(1);
concat(...)
const x = [].concat(...params)
reduce spread
const x = params.reduce((acc, val) => [...acc, ...val], []);