Using Node.js + Express without template engine

I have tried looking through all of the questions resolved by StackOverflow regarding people receiving this error:

Error: No default engine was specified and no extension was provided.

I feel like I have scoured every post on SO and none of the answers have corrected my code. There must be something else going on.

My issue that I am having is that I already created many html files before making a decision to use Node.js + Express for my back-end...so rather than worry about converting them all to a templating engine like pug or EJS, I just want to serve them from a static public folder in my directory.

From what I have researched, you do not need a templating engine to use Node.js + Express. But you do need to set up a static public folder to serve your files.

I have included the app.use(express.static(path.join(__dirname, 'public'))); in my app.js file. I have added a 'public' folder and put all of my static files inside of it, and in my routes file (my index.js file) I have written the following route:

router.get('/', (req, res) => { res.sendFile('./public/index.html'); });

I have tried changing it to the following:

1. res.sendFile('index');
2. res.sendFile(path.join(__dirname, 'index.html')
3. res.sendFile('../public/index.html');

I have also tried changing my static middleware syntax to just app.use(express.static('public')); and that didn't seem to change anything either.

All of these render the No default engine was specified and no extension was provided. error I provided above. I hate that I need to ask this questions when there are so many of the same questions on StackOverflow, but I am currently completely stumped at to what to do. Without further adieu, here is my code:

This is my file directory structure.

Here is my index.js file handling all my routes:

const express = require('express');
const router = express.Router();

router.get('/', (req, res) => {
  res.sendFile(path.join(__dirname, 'index.html'));
});

router.post('/', (req, res) => {

});

module.exports = router;

Here's my app.js file:

const express = require('express');
const path = require('path');
const cookieParser = require('cookie-parser');
const bodyParser = require('body-parser');
const routes = require('./routes/index');
const errorHandlers = require('./handlers/errorHandlers');


const app = express();

app.use('/', routes);

app.use(express.static(path.join(__dirname, 'public')));

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));

// If that above routes didnt work, we 404 them and forward to error handler
app.use(errorHandlers.notFound);

// One of our error handlers will see if these errors are just validation errors
app.use(errorHandlers.flashValidationErrors);

// Otherwise this was a really bad error we didn't expect! Shoot eh
if (app.get('env') === 'development') {
  /* Development Error Handler - Prints stack trace */
  app.use(errorHandlers.developmentErrors);
}

// production error handler
app.use(errorHandlers.productionErrors);

module.exports = app;

Here's my package.json:

{
  "name": "********",
  "version": "1.0.0",
  "devDependencies": {
    "grunt": "~0.4.1",
    "grunt-contrib-concat": "^1.0.1",
    "grunt-contrib-imagemin": "^1.0.1",
    "grunt-contrib-sass": "^1.0.0",
    "grunt-contrib-uglify": "^2.3.0",
    "grunt-contrib-watch": "^1.0.0",
    "webpack-dev-server": "^2.9.7"
  },
  "description": "",
  "main": "app.js",
  "scripts": {
    "start": "nodemon ./start.js"
  },
  "author": "****** ********",
  "license": "ISC",
  "dependencies": {
    "cookie-parser": "^1.4.3",
    "dotenv": "^4.0.0",
    "express": "^4.16.2",
    "mongod": "^2.0.0",
    "mongoose": "^4.13.7",
    "nodemon": "^1.14.1",
    "normalize.css": "^6.0.0"
  }
}

Here's my start.js file that runs when I run npm start:

const mongoose = require('mongoose');

// import environmental variables from our variables.env file
require('dotenv').config({ path: 'variables.env' });

mongoose.connect(process.env.DATABASE, { useMongoClient: true });
mongoose.Promise = global.Promise; 
mongoose.connection.on('error', (err) => {
  console.error(`${err.message}`);
});


const app = require('./app');
app.set('port', process.env.PORT || 7777);
const server = app.listen(app.get('port'), () => {
  console.log(`Express running → PORT ${server.address().port}`);
});