app.js

var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var bodyParser = require('body-parser');
var mongoose = require('mongoose');
mongoose.Promise = require('bluebird');

mongoose.connect('mongodb://localhost/mean-angular5', {
    useMongoClient: true,
    promiseLibrary: require('bluebird')
  })
  .then(() => console.log('connection succesful'))
  .catch((err) => console.error(err));

var book = require('./routes/book');
var app = express();

app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
  'extended': 'false'
}));
app.use(express.static(path.join(__dirname, 'dist')));
app.use('/books', express.static(path.join(__dirname, 'dist')));
app.use('/book', book);

// catch 404 and forward to error handler
app.use(function (req, res, next) {
  var err = new Error('Not Found');
  err.status = 404;
  next(err);
});

// error handler
app.use(function (err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

app.set('view engine', 'html');

module.exports = app;