Run results for: Preinitialized array size vs Push operations to an empty one.

Run details:

User agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.109 Safari/537.36

Browser: Chrome 72

Operating system: Windows 7

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
Preinitialized size - large difference	1102.2 Ops/sec
Push	4657.9 Ops/sec
Preinitialized size - small difference	4984.0 Ops/sec
Preinitilized size - no difference	4893.4 Ops/sec

Tests:

Preinitialized size - large difference
let arr = new Array(100000) for (var i=0; i<1000; i++) { arr[i] = Math.random; } arr = arr.slice(0, 1000)
Push
let arr =[] for (var i=0; i<1000; i++) { arr.push(Math.random); }
Preinitialized size - small difference
let arr = new Array(1200) for (var i=0; i<1000; i++) { arr[i] = Math.random; } arr = arr.slice(0, 1000)
Preinitilized size - no difference
let arr = new Array(1000) for (var i=0; i<1000; i++) { arr[i] = Math.random; }