step03.md

Step 3 - Communicate with the server

What is a router function?

When a request reaches the server, we need a way of responding to it. In comes the router function. The router function is just a function which receives requests and handles and directs them.

The router function always takes a request and response object and sends the response back to the client along with some information. You can decide what to send back in your response.

const router = (request, response) => {
  // deal with request and sending response
}

1. Create your own router function.

We are now making a router function with a custom message in our response. You can write any message you want.

Add the following code to server.js

const http = require('http');

const message = 'I am so happy to be part of the Node Girls workshop!';

const router = (request, response) => {

}

const server = http.createServer();
const port = 3000;

server.listen(port, ()=> {
  console.log(`Server is listening on port ${port}.  Ready to accept requests!`);
});

2. Tell your router function what to do

We want our router function to send our message in a response. To do that we will use one of the method of response object, which is: response.write(). You can find more about response.write() here

Every response has a header, which contains information about the response. We can add information to the header using response.writeHead(). The writeHead takes 3 parameters: status code, status message and header object, for now we will omit the status message, and use only the status code and the header object.

Add these line to the router function

const router = (request, response) => {

  response.writeHead(200, {"Content-Type": "text/html"});
  response.write(message); //response body
  response.end(); // finish response
}

3. Pass the router function to your server

The createServer() method takes a router function as an argument.

Pass your router function to createServer method

const server = http.createServer(router);

4. Rerun your server and go to your favourite browser

Rerun your server by typing again

node server.js

Type in your browser localhost:3000

If you see your message in the browser, congratulations you just sent your first response from the server.

Hint

It will get a bit annoying having to run the server any time we make a change from the terminal with node server.js . Install nodemon as a dev dependancy and write an npm script for starting the server file with nodemon.

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Keywords:

• 'status code'
• 'response.writeHead()'