Customising Output

In this step, you'll write a test, and the code to make that test pass.

In the last step you wrote some code for an API endpoint that output Hello world! What if instead we could pass in any string {{string}} to our endpoint, and get it to respond with "Hello, {{string}}!".

You have already written the code to do this in JavaScript Basics - the sayHello function in the strings module.

To achieve this, you will need to modify the existing endpoint, but firstly you should write a second test.

/* tests/strings.test.js */
describe('GET /hello/{string}', () => {
  it('returns "Hello, world!" when passed "world"', done => {
    ...
  });
 
  it('returns "Hello, turtle!" when passed "turtle"', done => {
    request(app)
      .get('/strings/hello/turtle')
      .then(res => {
        expect(res.status).toEqual(200);
        expect(res.body).toEqual({ result: 'Hello, turtle!' });
        done();
      });
  });
});

This test is basically the same as the previous one (note we've hidden some of the previous test above with ... for brevity) - but it sends the request to a slightly different path, and expects a slightly different response.

• Recap the :books: Express docs on routing
• Read the :books: Express docs on the req object
• Read the :books: Express docs on request route params

Challenge

Can you parameterise your existing route using route parameters to make the routes /strings/hello/world and /strings/hello/turtle both match the same route handler, with world or turtle available from the parameter's value?

Once you've done that, can you access the parameter and pass the value into your sayHello method, in order to return the appropriate data?

You will need to require the sayHello function from the ./lib/strings file.

Extra credit

Fire up your server locally with npm start and use Postman to visit your new routes.

• /strings/hello/world
• /strings/hello/turtle

Solution

Try your best to solve the above first without looking at the solution.

• Find the solution to the above challenge here.