Node JS Stream Only works on first iteration - node.js

Question

I have a simple node app that parses a csv file into a string. In my server file, I call a module that runs makes a stream and pipes it into my parser.
The problem is that is code works perfectly the first time it is run, but fails after that. I've gotten a "Write after End" error so I believe there is something wrong with the stream or parser variable not being reset properly after each use. Thanks for any help!
const express = require('express');
const app = express();
const path = require('path');
const port = process.env.PORT || 3000;
const formidable = require('formidable');
const parser = require('./csvparse.js');
const fs = require('fs');
//send the index page on a get request
app.listen(port, () => console.log('Example app listening on port: ' + port));
app.get('*', (req, res) => res.sendFile(path.join(__dirname + "/index.html")));
app.post('/upload', function(req, res) {
//upload the file from the html form
var form = new formidable.IncomingForm();
form.parse(req,function(err, fields, files) {
if (err) throw err;
//get the path to the uploaded file for the parser to use
var filePath = files.spinFile.path;
parser(filePath, function(data) {
if (data == null) {
res.sendFile(path.join(__dirname + "/index.html"));
}
res.send("<code>" + data + "</code>");
});
});
});
The module export function looks like this:
module.exports = function(filePath, cb) {
var stream = fs.createReadStream(filePath);
stream.pipe(parser);
//when the stream is done, songsLog is complete and ready to be returned
stream.on('close', function() {
cb(songsLog);
});
};

Answer 1

Try wrapping the contents of your module.exports in another function.
module.exports = function(filepath, cb) {
function parse(filepath) {
const stream = fs.createReadStream(filepath)
etc...
}
return {
parse
}
}
then from your route, call parser.parse('file.txt') and you should have a new read stream.