In my node.js application I did a
npm install btoa-atob
The 'btoa-atob' module does not export a programmatic interface, it only provides command line utilities.
If you need to convert to Base64 you could do so using Buffer:
console.log(new Buffer('Hello World!').toString('base64'));
Reverse (assuming the content you're decoding is a utf8 string):
console.log(new Buffer(b64Encoded, 'base64').toString());