Pfthb

I have a very simple node.js app which successfully processes a file (from formidable form) but the download of the result file fails. The download html

<p><input type="text" value = "tx-AllSerums.xlsx"><br>
<a href="/transformed/tx-AllSerums.xlsx"
download="All Serums.xlsx">Download transformed file</a>
</p>

The result files are written to the directory structure from where I run node (the 'transformed' dir is in the dir in which I run node).
When I click on the above href I get console output but no file save dialog. (Should the server even get this event?)
When I kill the node server, up pops the file save dialog. Of course the save fails: Network error.
I'm currently running everything on my workstation: Ubuntu 18.04; Chrome 70.0.3538.77, node v10.13.0

I've found that the file save dialog does appear but a very long time after the click. But the server is still up and the save operation still fails: Network error.

Adding res.end() to the block catching the download click gets the dialog up immediately. Now I successfully download a zero length file. Oddly I find that encouraging.

var formidable = require('formidable');
var util = require("util");
var http = require('http');
var url = require('url');
var fs = require('fs');
var java = require("java");
var proc = require("process");

java.classpath.push("/home/u0138544/fake/prep-1.jar");
java.classpath.push("/home/u0138544/fake/SRTDependancies-1.jar");
console.log(proc.cwd());
http.createServer(function (req, res) 
 txName = "";
 if (req.url == '/fileupload' && req.method.toLowerCase() == 'post') 
 var form = formidable.IncomingForm();
 form.keepExtensions = true;
 var excelFilePath;
 var origName;
 form.parse(req , function (err, fields, files) 
 excelFilePath = files.filetoupload.path;
 console.log("upload " + excelFilePath);
 origName = files.filetoupload.name;
 txName = "tx-" + origName.replace(/s/g, "");
 console.log( "txname = " + txName);
 //just for formatter
 var clz = "edu.utah.camplab.xlsx.SampleReportTransformer";
 var tx = java.newInstanceSync(clz);
 java.callMethodSync(tx, "run", excelFilePath, "./transformed/" + txName);
 res.writeHead(200, 'Content-Type': 'text/html');
 res.write('<p>');
 res.write('<input type="text" value = "' + txName +'"><br>');
 res.write('<a href="transformed/' + txName + '" download="' + origName +'">Download transformed file</a></p>');
 return res.end();
 );
 
 else if (req.url.includes('transformed') && 
 req.method.toLowerCase() == 'get') 
 console.log("download attribute doesn't work")
 res.end();
 
 else 
 res.writeHead(200, 'Content-Type': 'text/html');
 res.write('<form action="fileupload" method="post" enctype="multipart/form-data">');
 res.write('<input type="file" name="filetoupload" label="Pick a file"><br>');
 res.write('<input type="submit">');
 res.write('</form>');
 return res.end();
 
).listen(15080);