How to convert base64 stream into string and write into another file?

Question

I am getting message stream from email body and this stream is in base64 formate I want to decode the stream.I am using 'base64-stream' which is npm module to decode the stream but I am getting error.

TypeError: base64.decode is not a function

 function buildAttMessageFunction(attachment) {
 var filename = attachment.params.name;
 var encoding = attachment.encoding;
 return function (msg, seqno) {
 var prefix = '(#' + seqno + ') ';
 msg.on('body', function(stream, info) {
 //Create a write stream so that we can stream the attachment to file;
 console.log(prefix + 'Streaming this attachment to file', filename, info);
 var writeStream = fs.createWriteStream(filename);
 writeStream.on('finish', function() {
 console.log(prefix + 'Done writing to file %s', filename);
 });
 //stream.pipe(writeStream); this would write base64 data to the file.
 //so we decode during streaming using 
 if (toUpper(encoding) === 'BASE64') {
 //the stream is base64 encoded, so here the stream is decode on the fly and piped to the write stream (file)
 stream.pipe(base64.decode()).pipe(writeStream);
 } else {
 //here we have none or some other decoding streamed directly to the file which renders it useless probably
 stream.pipe(writeStream);
 }
 });
 msg.once('end', function() {
 console.log(prefix + 'Finished attachment %s', filename);
 });
 };
}

Answer 1

I guess you need to use this way

const {Base64Decode} = require("base64-stream");
stream.pipe(new Base64Decode()).pipe(writeStream);