Short Utils

utils.js

// String ranges: strange('A-Za-z0-9+/') -> "ABCDEFGHIJKLMNOPQRSTUVWXYabcdefghijklmnopqrstuvwxy012345678+/"
const strange = s => s.replace(/(.)-(.)/g, (_, x, y) => { for (var i = x.charCodeAt(0) + 1; i < y.charCodeAt(0); i++) x += String.fromCharCode(i); return x })

// Base64 encoding of Uint8Array of ArrayBuffer and decoding to Uint8Array
const encodeBase64 = a => btoa(Array.from(a instanceof ArrayBuffer ? new Uint8Array(a) : a).map(x => String.fromCharCode(x)).join(''));
const encodeBase64url = a => encodeBase64(a).replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, ''); // no padding
const decodeBase64 = s => Uint8Array.from(atob(s), x => x.charCodeAt(0));
// TODO: decodeBase64url