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Step 3 - Communicate with the server

git checkout step3
git merge step2

What is a handler function?

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

The handler 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.

function handler (request, response) {
  //dealing with request and sending response
}

1. Create your own handler function.

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

Add the following code to server.js

var http = require('http');

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

function handler (request, response) {

}


var server = http.createServer();

server.listen(3000, function () {

    console.log("Server is listening on port 3000.  Ready to accept requests!");
});

2. Tell your handler function what to do

We want our handler 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 2 parameters: status code and header object.

Add these line to the handler function

function handler (request, response) {

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

3. Pass the handler function to your server

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

Pass your handler function to createServer method

var server = http.createServer(handler);

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.

Commit your changes

git add .
git commit -m 'enter relevant message'
git push origin step3

next step >>>

Keywords:

  • status code
  • response.writeHead()