Run results for: spread vs push vs concat for large arrays

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.106 Safari/537.36

Browser: Chrome 91

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
spread	1034.8 Ops/sec
spread (combined)	1179.3 Ops/sec
push	665.1 Ops/sec
push (combined)	460.5 Ops/sec
concat	3312.8 Ops/sec
concat (nested)	2388.6 Ops/sec

Script Preparation code:

var size = 50000;
var iterations = 1;

var arr1 = [];
var arr2 = [];

for (var i = 0; i < size; i++) {
  arr1.push({foo: i, bar: i});
  arr2.push({foo: i, bar: i});
}

Tests:

spread
var res = []; for (var i = 0; i < iterations; i++) { res = [...res, ...arr1]; res = [...res, ...arr2]; }
spread (combined)
var res = []; for (var i = 0; i < iterations; i++) { res = [...res, ...arr1, ...arr2]; }
push
var res = []; for (var i = 0; i < iterations; i++) { res.push(...arr1); res.push(...arr2); }
push (combined)
var res = []; for (var i = 0; i < iterations; i++) { res.push(...arr1, ...arr2); }
concat
var res = []; for (var i = 0; i < iterations; i++) { res = res.concat(arr1).concat(arr2); }
concat (nested)
var res = []; for (var i = 0; i < iterations; i++) { res = res.concat(arr1.concat(arr2)); }

Run results for: spread vs push vs concat for large arrays

spread

spread (combined)

push

push (combined)

concat

concat (nested)