Run results for: copyWithin: is it fast?

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 14_7 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/92.0.4515.90 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 92

Operating system: iOS 14.7

Device Platform: Mobile

Date tested: 3 years ago

Test name	Executions per second
Uint8 copyWithin	88114.7 Ops/sec
Int8 Iteration	16.6 Ops/sec
Uint32 copy within	19979.0 Ops/sec
.set	83834.9 Ops/sec

Script Preparation code:

// starting with a plain array buffer, what is fastest?
var buffer = new ArrayBuffer(1024 * 1024);
var originalIntView = new Uint8Array(buffer);
for (var i = 0; i < originalIntView.length; i++) {
  originalIntView[i] = Math.round(Math.random() * 256);
}

Tests:

Uint8 copyWithin
originalIntView.copyWithin(0, 512*1024, 1024*1024)
Int8 Iteration
for (var i = 0; i < 1024 * 512; i++) { originalIntView[i] = originalIntView[i + 1024 * 512]; }
Uint32 copy within
var int32View = new Uint32Array(originalIntView.buffer, originalIntView.byteOffset, originalIntView.byteLength / 4); for (var i = 0; i < 1024 * 512 / 4; i++) { int32View[i] = int32View[i + 1024 * 512 / 4]; }
.set
var other = new Uint8Array(originalIntView.buffer, originalIntView.byteOffset + originalIntView.byteLength / 2, originalIntView.byteLength / 2) originalIntView.set(other, 0)

Run results for: copyWithin: is it fast?

Is copyWithin fast?

Uint8 copyWithin

Int8 Iteration

Uint32 copy within

.set