• Hello World at Command Prompt
• Hello World HTTP Server
• Counter

Learning Node.JS Programming

April 2014 - Better late than never, but I should have begun this process a few months ago.

• http://jothut.com/cgi-bin/junco.pl/tag/nodejs
• http://jothut.com/cgi-bin/junco.pl/b/17499/NodeJS-for-newbies
• http://nodejs.org
• https://www.npmjs.org
• http://nodejs.org/docs/v0.4.11/api/http.html#http.request
• http://package.json.nodejitsu.com
• http://inessential.com/2013/12/09/getting_started_with_node_js_for_cocoa_
• http://inessential.com/2013/12/09/getting_started_with_web_services_using_
• http://expressjs.com/4x/api.html
• http://howtonode.org/hello-node
• http://www.2ality.com/2011/12/nodejs-shell-scripting.html
• http://www.theprojectspot.com/tutorial-post/Node-js-for-beginners-part-1-hello-world/2
• http://www.theprojectspot.com/tutorial-post/nodejs-for-beginners-callbacks/4

Hello World at Command Prompt

Open up a text file and enter:

// Call the console.log function.
console.log("Hello World");

Save file as hello-console.js and then at the command prompt, execute:
node hello-console.js

Obviously, that produces:
Hello World

Hello World HTTP Server

Add the following code to a file called:
hello-server.js

---

// Load the http module to create an http server.
var http = require('http');

// Configure our HTTP server to respond with Hello World to all requests.
var server = http.createServer(function (request, response) {
  response.writeHead(200, {"Content-Type": "text/plain"});
  response.end("Hello World\n");
});

// Listen on port 8080, IP defaults to 127.0.0.1
server.listen(8080);

// Put a friendly message on the terminal
console.log("Server running at http://127.0.0.1:8080/");

---

Execute the code with:
node hello-server.js

The following message will be displayed to the console:
Server running at http://127.0.0.1:8080/

Point the browser to the domain/sub domain of the server with the port included. Example:
http://nodejs.soupmode.com:8080

If running the server and the browser on the same machine, use: http://localhost:8080

If the above server code is running, then the following will be displayed in the browser:
Hello World

To stop this server app, hit Ctrl-C at the command prompt.

Counter

Add the following code to counter.js

---

var http = require('http');

var userCount = 0;
http.createServer(function (request, response) {
    console.log('New connection');
    userCount++;

    response.writeHead(200, {'Content-Type': 'text/plain'});
    response.write('Hello!\n');
    response.write('We have had '+userCount+' visits!\n');
    response.end();
}).listen(8080);

console.log('Server started');

---

Execute the code with:
node counter.js

The message displayed to the console will say:
Server started

When accessing the server at port 8080 in the browser, the following will be displayed to the browser:
Hello!
We have had 1 visits!

Back at the server, the console display will say:
New connection
New connection

A refresh on the browser will cause the following message to be sent by the counter.js app:
Hello!
We have had 3 visits!

The counter increments by two.

Explanation from the article :

Note: You might see the counter going up by two for each request, this is because your browser is requesting the favicon from the server (http://localhost:8080/favicon.ico).

You should also see that Node.js is logging each request it receives to the console.

The main thing we're doing here is setting a 'userCount' variable and incrementing on each request. We're then writing the 'userCount' in the response text.

#nodejs - #programming - #javascript - #howto