Advanced Express Web Application Development

404 handling middleware

In order to handle a 404 Not Found response, let's add a 404 not found middleware. Let's write a test, ./test/heartbeat.js; the content type returned should be JSON and the status code expected should be 404 Not Found:

describe('vision heartbeat api', function(){
  describe('when requesting resource /missing', function(){
    it('should respond with 404', function(done){
      request(app)
      .get('/missing')
      .expect('Content-Type', /json/)
      .expect(404, done);
    })
  });
});

Now, add the following middleware to ./lib/middleware/notFound.js. Here we export a function called index and call res.json, which returns a 404 status code and the message Not Found. The next parameter is not called as our 404 middleware ends the request by returning a ...