webserver.js

var express = require('express');
var fs = require('fs');
var path = require('path');
var tessel = require('tessel');

var app = express();
var mount = '/mnt/sda1'; // usb drive in Tessel; top USB slot
// var mount = '/Volumes/USB\ DISK'; // local machine's USB drive
var port = 8080;

// Respond to the request with our index.html page
function sendFile (filename, request, response) {
  if (filename.includes('.html')) {
    response.writeHead(200, {"Content-Type": "text/html"});
  } else if (filename.includes('.js')) {
    response.writeHead(200, {"Content-Type": "text/javascript"});
  } else if (filename.includes('.css')) {
    response.writeHead(200, {"Content-Type": "text/css"});
  }

  console.log('about to send', filename);

  fs.readFile(path.join(__dirname, filename), function (err, content) {
    if (err) { throw new Error(err); }

    response.end(content);
  });
}

app.get('/', function (request, response) {
  sendFile('/index.html', request, response);
});

app.get('/frontend.js', function(request, response) {
  sendFile('/frontend.js', request, response);
});

app.get('/cutestrap.min.css', function(request, response) {
  sendFile('/cutestrap.min.css', request, response);
});

// Make available the files in the USB drive inserted into the top port
app.use(express.static(mount));

// Endpoint for initial AJAX request from index.html
app.get('/dir', function (request, response) {
  fs.readdir(mount, function(err, files) {
    if (err) {throw new Error(err); }
    console.log('working on that ajax');

    response.writeHead(200, {"Content-Type": "application/json"});

    files = files.filter(function(f) {
      return f[0] !== '.';
    });

    response.end(JSON.stringify({files: files}));
  });
});

// Add routes for files that are, in reality, *directories*!
app.get(/[^A-z0-9\s]/, function (request, response) {

  // todo: improve handling of the favicon.ico file
  if (request.url.includes('favicon')) {return; }

  var newDir = request.url.replace(/%20/g, ' ');

  fs.readdir(path.join(mount, newDir), function(err, files) {
    if (err) {throw new Error(err); }

    response.writeHead(200, {"Content-Type": "application/json"});

    // Does not return hidden files
    files = files.filter(function(f) {
      return f[0] !== '.';
    });

    // might want to serve another template-like HTML page
    // and send this JSON that way
    response.end(JSON.stringify({files: files}));
  });
});

app.listen(port, function() {
  console.log('Server running at http://192.168.1.101:' + port);
});