Run results for: JavaScript Uint8Array to Base64: all

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36

Browser: Chrome 142

Operating system: Windows

Device Platform: Desktop

Date tested: 8 months ago

Test name	Executions per second
✓ toBase64	7,852,182 Ops/sec
Chunk	333,819 Ops/sec
Apply	332,393 Ops/sec
Concat	223,895 Ops/sec
btoa	95,293 Ops/sec
Spread	54,976 Ops/sec
FileReader	4,580 Ops/sec

Script Preparation code:

function bytesToBase64ByFileReader(bytes) {
    return new Promise(r => {
        const reader = new FileReader()
        reader.onload = () => r(reader.result)
        reader.readAsDataURL(new Blob([bytes]))
    }).then(url => url.slice(url.indexOf(",") + 1));
}

function bytesToBase64ByBtoa(bytes) {
    return btoa(bytes.reduce((data, byte) => data + String.fromCharCode(byte), ""));
}

function base64UrlEncodeConcat(bytes) {
    let binary = '';
    for (let i = 0; i < bytes.length; i++)
      binary += String.fromCharCode(bytes[i]);
    return btoa(binary);
}

function base64UrlEncodeSpread(bytes) {
    let binary = String.fromCharCode(...bytes);
    return btoa(binary);
}

function base64UrlEncodeApply(bytes) {
    let binary = String.fromCharCode.apply(null, bytes);
    return btoa(binary);
}

function base64UrlEncodeChunk(bytes) {
  let binaryString = '';
  for (let i = 0; i < bytes.length; i += 49152) { // Use chunk size divisible by 3
    binaryString += String.fromCharCode.apply(null, bytes.subarray(i, i + 49152));
  }
  return btoa(binaryString);
}

const bytes1K = new Uint8Array(1024);
for (const bytes of [bytes1K])
    for (let i = 0; i < bytes.length; i += 65536)
        crypto.getRandomValues(bytes.subarray(i, i + 65536));

Tests:

FileReader [Async/Deferred]
await bytesToBase64ByFileReader(bytes1K); deferred.resolve();
btoa
bytesToBase64ByBtoa(bytes1K);
Concat
base64UrlEncodeConcat(bytes1K);
Spread
base64UrlEncodeSpread(bytes1K);
Apply
base64UrlEncodeApply(bytes1K);
Chunk
base64UrlEncodeChunk(bytes1K);

Run results for: JavaScript Uint8Array to Base64: all

toBase64 is usually the fastest, but may not be supported by older browsers.

FileReader [Async/Deferred]

btoa

Concat

Spread

Apply

Chunk