CODE EXAMPLE FOR JAVASCRIPT

base64 to base64url javascript

/**
 * Function that converts a base64 string into a base64url string
 * @param {string} input - The string to convert
 */
function base64ToBase64url(input) {
  // Replace non-url compatible chars with base64url standard chars and remove leading =
  return input
    .replace(/+/g, '_')
    .replace(///g, '-')
    .replace(/=+$/g, '');
}