fullstackapp/nusmoney_backend/app.js

var createError = require('http-errors');
var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var logger = require('morgan');
var cors = require("cors");   // add this line

var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');
var accountsRouter = require('./routes/accounts');
var transactionsRouter = require('./routes/transactions');
var messagesRouter = require('./routes/messages');

var app = express();

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'pug');

app.use(logger('dev'));
// For Express 4.16+, no need "body-parser" module
// Thus, can exclude
//  - require('body-parser');
//  - app.use(body-parser.json());
//  - replace with "app.use(express.json())"
// https://medium.com/@mmajdanski/express-body-parser-and-why-may-not-need-it-335803cd048c
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use(cors());  // add this line
app.use('/', indexRouter);
app.use('/users', usersRouter);
app.use('/accounts', accountsRouter);
app.use('/transactions', transactionsRouter);
app.use('/messages', messagesRouter);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  next(createError(404));
});

// 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');
});

module.exports = app;