/**
 * string转为base64
 */
function stringToBase64(str) {
  return new Buffer.from(str).toString("base64");
}

/**
 * base64转字符串
 */
function base64ToString(b64) {
  return new Buffer.from(b64, "base64").toString();
}

// 转为base64
var str1 = "aaabbbccc";
console.log(stringToBase64(str1));

// base64反解析为字符串
var str2 = "YWFhYmJiY2Nj";
console.log(base64ToString(str2));