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/605.1.15 (KHTML, like Gecko) Version/17.3.1 Safari/605.1.15

Browser: Safari 17

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
reduce + Array.prototype.concat	430620.4 Ops/sec
Array.prototype.flat	12876.4 Ops/sec
concat(...)	210556.9 Ops/sec
reduce spread	86643.5 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], []);