Run results for: array concat vs push vs spread

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:81.0) Gecko/20100101 Firefox/81.0

Browser: Firefox 81

Operating system: Mac OS X 10.12

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
push	9061.0 Ops/sec
concat	161.9 Ops/sec
concat spread	18504.3 Ops/sec
push apply	10655.4 Ops/sec
concat apply	41611.9 Ops/sec

Script Preparation code:

const arrayCount = 500;
const arraySize = 4;

var arrays = [];
for(let i = 0; i < arrayCount; i++) {
  arrays.push(Array.from({length: arraySize}, () => Math.floor(Math.random() * 40)));
}

Tests:

push
let result = []; arrays.forEach(curr => {result.push(...curr)});
concat
let result = []; arrays.forEach(curr => {result = result.concat(curr)});
concat spread
let result = []; result = result.concat(...arrays);
push apply
let result = []; arrays.forEach(curr => {Array.prototype.push.apply(result, curr);});
concat apply
let result = []; result = Array.prototype.concat.apply(result, arrays);

Run results for: array concat vs push vs spread

testing speed of concatenating many arrays

push

concat

concat spread

push apply

concat apply