Safe Base64 codecs for JavaScript

A pure JavaScript port of the libsodium base64 codecs.

Features:

• Supports traditional and URL-safe variants, with or without padding
• Rejects non-canonical padding
• Constant-time (best-effort), suitable for encoding/decoding secrets
• Characters can be ignored by the decoder

Usage:

• Traditional alphabet, padding:

const codec = new Base64(true);
const b64 = codec.encode(data);
const data2 = codec.decode(b64);

• Traditional alphabet, no padding:

const codec = new Base64(false);
const b64 = codec.encode(data);
const data2 = codec.decode(b64);

• URL-safe, no padding:

const codec = new Base64UrlSafe(false);
const b64 = codec.encode(data);
const data2 = codec.decode(b64);

• URL-safe, padding, ignoring spaces and \n:

const codec = new Base64UrlSafe(true, " \n");
const b64 = codec.encode(data);
const data2 = codec.decode(b64);