Run results for: setArray forward vs backwards

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36

Browser: Chrome 138

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

backward when same

116K/s

forward when same

114K/s

forward when empty

110K/s

backward when empty

103K/s

View exact numbers

Test name	Executions per second
✓ backward when same	115,969 Ops/sec
forward when same	113,782 Ops/sec
forward when empty	110,332 Ops/sec
backward when empty	102,601 Ops/sec

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

const src = Array(10000);
for (let i = 0, end = src.length; i < end; i += 1) {
  src[i] = i;
}

function setArrayForward(dst, src) {
  dst.length = src.length;
  for (let i = 0, end = dst.length; i < end; i += 1) {
    dst[i] = src[i];
  }
}

function setArrayBackward(dst, src) {
  dst.length = src.length;
  for (let i = dst.length; i > 0; i -= 1) {
    dst[i - 1] = src[i - 1];
  }
}

Tests:

forward when empty
const dst = []; setArrayForward(dst, src);
forward when same
const dst = src.slice(); setArrayForward(dst, src);
backward when empty
const dst = []; setArrayBackward(dst, src);
backward when same
const dst = src.slice(); setArrayBackward(dst, src);