Run results for: TextDecoder compared to String.fromCharCode

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:145.0) Gecko/20100101 Firefox/145.0

Browser: Firefox 145

Operating system: Linux

Device Platform: Desktop

Date tested: 7 months ago

TextDecoder, subarray

428K/s

TextDecoder, new uint8array

256K/s

String.fromCharCode, subarray

14K/s

View exact numbers

Test name	Executions per second
✓ TextDecoder, subarray	428,186 Ops/sec
TextDecoder, new uint8array	255,830 Ops/sec
String.fromCharCode, subarray	13,931 Ops/sec

Script Preparation code:

const testLength = 1000;
const startSlice = 300;
const endSlice = 700;

const getRandomCharCode = () => Math.floor(Math.random() * 26) + 97; // a-z letters
const bytes = Array.from({length: testLength}, () => getRandomCharCode());

var buffer = new Uint8Array(bytes);
var decoder = new TextDecoder(); // default 'utf-8' or 'utf8'

Tests:

String.fromCharCode, subarray
String.fromCharCode(...buffer.subarray(startSlice, endSlice));
TextDecoder, new uint8array
const slice = new Uint8Array(buffer.buffer, startSlice, endSlice - startSlice); decoder.decode(slice);
TextDecoder, subarray
decoder.decode(buffer.subarray(startSlice, endSlice))