Node.js - First Application
A Node.js application consists of the following three important components
- Import required modules − We use the require directive to load Node.js modules.
- Create server − A server which will listen to client's requests similar to Apache HTTP Server.
- Read request and return response − The server created in an earlier step will read the HTTP request made by the client which can be a browser or a console and return the response.
Creating Node.js Application :
Initially install http server using command as npm install http
Step 1 - Import Required Module :
We use the require directive to load the http module and store the returned HTTP instance into an http variable as follows −
var http = require("http");
We use the created http instance and call http.createServer() method to create a server instance and then we bind it at port 3000 using the listen method associated with the server instance. Pass it a function with parameters request and response. Write the sample implementation to always return "Hello World".
The above code is enough to create an HTTP server which listens, i.e., waits for a request over 3000 port on the local machine.
Step 3 - Testing Request & Response
Let's put step 1 and 2 together in a file called app.js and start our HTTP server as shown below −
Now execute the app.js to start the server as follows − 3000
Verify the Output. Server has started.
Server running at http://127.0.0.1:3000/. Open the browser and past the link.