index.js

//express is the framework we're going to use to handle requests
const express = require("express");
//Create a new instance of express
const app = express();

let middleware = require("./utilities/middleware");

const bodyParser = require("body-parser");
//This allows parsing of the body of POST requests, that are encoded in JSON
app.use(bodyParser.json());

//pg-promise is a postgres library that uses javascript promises
const pgp = require("pg-promise")();
//We have to set ssl usage to true for Heroku to accept our connection
pgp.pg.defaults.ssl = true;
app.use("/login", require("./routes/login.js"));
app.use("/register", require("./routes/register.js"));

/*
 * Return HTML for the / end point.
 * This is a nice location to document your web service API
 * Create a web page in HTML/CSS and have this end point return it.
 * Look up the node module 'fs' ex: require('fs');
 */
app.get("/", (req, res) => {
  res.writeHead(200, { "Content-Type": "text/html" });
  for (i = 1; i < 7; i++) {
    //write a response to the client
    res.write("<h" + i + ' style="color:blue">Hello World!!</h' + i + ">");
  }
  res.end(); //end the response
});

/*
 * Heroku will assign a port you can use via the 'PORT' environment variable
 * To accesss an environment variable, use process.env.<ENV>
 * If there isn't an environment variable, process.env.PORT will be null (or undefined)
 * If a value is 'falsy', i.e. null or undefined, javascript will evaluate the rest of the 'or'
 * In this case, we assign the port to be 5000 if the PORT variable isn't set
 * You can consider 'let port = process.env.PORT || 5000' to be equivalent to:
 * let port; = process.env.PORT;
 * if(port == null) {port = 5000}
 */

app.listen(process.env.PORT || 5000, () => {
  console.log("Server up and running on port: " + (process.env.PORT || 5000));
});