Run results for: array concat vs push vs spread

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.121 Safari/537.36

Browser: Chrome 85

Operating system: Mac OS X 10.12.6

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
push	49541.8 Ops/sec
concat	2963.5 Ops/sec
concat spread	55346.9 Ops/sec
push apply	7518.7 Ops/sec
concat apply	54247.4 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