base64UrlEncode and base64UrlDecode functions in JS/TS

base64url.ts

/*
  Basically, base64URL is a modification of common base64 standard containing following changes:
   * Replaces "+" by "-" (minus)
   * Replaces "/" by "_" (underline)
   * Does not require a padding character
   * Forbids line separators
  Considering above, base64url string may be safely used as part of the URL without any further encoding.

  For more details please see https://base64.guru/standards/base64url
*/

function base64UrlEncode(data: string): string {
  return btoa(data).replace(/=+$/,'').replace(/\+/g,'-').replace(/\//g,'_');
}

function base64UrlDecode(data: string): string {
  return atob(data.replace(/-/g,'+').replace(/_/g,'/'));
}