Node.js Tutorial - Node.js Introduction

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Node.js is a platform for writing network and web applications.

Node.js is built around an event-driven nonblocking model of programming.

Running Node.js and "Hello World!"

Create a file called hello.js:

/**
  * comment.
  */
console.log("Hello World!");

Now, we can execute this file from the command line with

node hello.js

And you should see this output:

Variables

Variables are defined in JavaScript using the var keyword.

For example, the following code segment creates a variable foo and logs it to the console.

var myData = 123; 
console.log(myData);

The code above generates the following result.

The JavaScript runtime has the opportunity to define a few global variables that we can use in our code.

One of them is the console object.

The console object contains a member function (log), which takes any number of arguments and prints them to the console.

First Web Server

Enter and save the following into a file called web.js :

var http = require("http");
/*from   www .j  a  v  a2  s.  com*/
function process_request(req, res) {
     var body = 'Thanks for calling!\n';
     var content_length =  body.length ;
     res.writeHead(200, {
         'Content-Length': content_length,
         'Content-Type': 'text/plain'
     });
     res.end(body);
}
var s = http.createServer(process_request);
s.listen(8080);

To run it, simply type

node web.js

Your computer now has a web server running on port 8080.

We can type http://localhost:8080 into a web browser.

or use

curl -i http://localhost:8080

You should now see something similar to the following:

HTTP/1.1 200 OK
Content-Length: 20
Content-Type: text/plain
Date: Tue, 15 Feb 2013 03:05:08 GMT
Connection: keep-alive

Thanks for calling!

curl

We can download the Windows binaries for curl by visiting http://curl.haxx.se/download.html and looking there for the "Win32 - Generic" section.

Download one of the highlighted binaries, preferably one with support for SSL and SSH, unpack it, and put curl.exe somewhere in your PATH or user directory.

To launch it, in the command prompt or PowerShell, just type

C:\Users\abc\curl --help

Wget

wget is a great alternative for curl.

We can download it from http://users.ugent.be/~bpuype/wget/.

To learn more, view the help:

C:\Users\abc\wget  --help

Note

To stop the server from running, you simply press Ctrl+C.

It is smart enough to clean up everything and shut down properly.

To debug, just add the debug flag before the name of your program:

node debug web.js

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