text: const atob = require('atob');
  const btoa = require('btoa');
  
  class Base64Util {
  
      /**
       * Convert a base64 encoded string to a Uint8Array.
       * @param {string} base64 - a base64 encoded string.
       * @return {Uint8Array} - a decoded Uint8Array.
       */
      static base64ToUint8Array (base64) {
          const binaryString = atob(base64);
          const len = binaryString.length;
          const array = new Uint8Array(len);
          for (let i = 0; i < len; i++) {
              array[i] = binaryString.charCodeAt(i);
          }
          return array;
      }
  
      /**
       * Convert a Uint8Array to a base64 encoded string.
       * @param {Uint8Array} array - the array to convert.
       * @return {string} - the base64 encoded string.
       */
      static uint8ArrayToBase64 (array) {
          const base64 = btoa(String.fromCharCode.apply(null, array));
          return base64;
      }
  
      /**
      * Convert an array buffer to a base64 encoded string.
      * @param {array} buffer - an array buffer to convert.
      * @return {string} - the base64 encoded string.
      */
      static arrayBufferToBase64 (buffer) {
          let binary = '';
          const bytes = new Uint8Array(buffer);
          const len = bytes.byteLength;
          for (let i = 0; i < len; i++) {
              binary += String.fromCharCode(bytes[ i ]);
          }
          return btoa(binary);
      }
  
  }
  
  module.exports = Base64Util;