jwt encoder

function encodeJWT(payload){
  function base64urlEncode(str) {
    return window.btoa(unescape(encodeURIComponent(str)))
  }
  const segments = [
    base64urlEncode(JSON.stringify({ typ: 'JWT', alg: 'HS256' })),
    base64urlEncode(JSON.stringify(payload)),
    'fake-signature'
  ];
  return segments.join('.');
}