Node JS Basic Example
Example:1
var http = require('http');
var dt = require('./mymodule');
http.createServer(function (req, res)
{
res.writeHead(200, {'Content-Type': 'text/html'});
res.write("The date and time is currently: " +dt.myDateTime());
//res.write("addtion of 2 numbers:" f1(7,9));
res.end();
}).listen(8000);
Example:2
cal.js
var Addition = require('./Addition');
var a=10, b=5;
console.log("Addition : "+Addition.add(a,b));
console.log("Subtraction : "+Addition.sub(a,b));
console.log("Multiplication : "+Addition.mul(a,b));
console.log("Division : "+Addition.div(a,b));
Addition.js
var exports = module.exports = {};
exports.add = function(a, b)
{
return a + b;
}
exports.sub = function(a, b)
{
return a - b;
}
exports.mul = function(a, b)
{
return a * b;
}
exports.div = function(a, b)
{
return a / b;
}
Run code: node cal.js
Example:3 Sum of n numbers program
var n=[10,20,30,40,100];
var sum=0;
for(i=0;i<n.length;i++)
{
sum=sum+n[i];
}
console.log("your sum is " +sum);
Example:4
buf = new Buffer(26);
for (var i = 0 ; i < 26 ; i++)
{
buf[i] = i + 97;
}
console.log( buf.toString('ascii')); // outputs: abcdefghijklmnopqrstuvwxyz
console.log( buf.toString('ascii',0,5)); // outputs: abcde
console.log( buf.toString('utf8',0,5)); // outputs: abcde
console.log( buf.toString(undefined,0,5)); // encoding defaults to 'utf8', outputs abcde
Example:5
var fs = require("fs");
var data = 'Solution of Program';
// Create a writable stream
var writerStream = fs.createWriteStream('output.txt');
// Write the data to stream with encoding to be utf8
writerStream.write(data,'UTF8');
// Mark the end of file
writerStream.end();
// Handle stream events --> finish, and error
writerStream.on('finish', function() {
console.log("Write completed.");
});
writerStream.on('error', function(err){
console.log(err.stack);
});
console.log("Program Finished");
Example:6
var fs = require("fs");
// Asynchronous read
fs.readFile('input.txt', function (err, data) {
if (err) {
return console.error(err);
}
console.log("Asynchronous read: " + data.toString());
});
// Synchronous read
var data = fs.readFileSync('input.txt');
console.log("Synchronous read: " + data.toString());
console.log("Program Ended");
Example:7
// Import events module
var events = require('events');
// Create an eventEmitter object
var eventEmitter = new events.EventEmitter();
// Create an event handler as follows
var connectHandler = function connected() {
console.log('connection succesful.');
// Fire the data_received event
eventEmitter.emit('data_received');
}
// Bind the connection event with the handler
eventEmitter.on('connection', connectHandler);
// Bind the data_received event with the anonymous function
eventEmitter.on('data_received', function() {
console.log('data received succesfully.');
});
// Fire the connection event
eventEmitter.emit('connection');
console.log("Program Ended.");
Example:8
var events = require('events');
var eventEmitter = new events.EventEmitter();
// listener #1
var listner1 = function listner1() {
console.log('listner1 executed.');
}
// listener #2
var listner2 = function listner2() {
console.log('listner2 executed.');
}
// Bind the connection event with the listner1 function
eventEmitter.addListener('connection', listner1);
// Bind the connection event with the listner2 function
eventEmitter.on('connection', listner2);
var eventListeners = require('events').EventEmitter.listenerCount
(eventEmitter,'connection');
console.log(eventListeners + " Listner(s) listening to connection event");
// Fire the connection event
eventEmitter.emit('connection');
// Remove the binding of listner1 function
eventEmitter.removeListener('connection', listner1);
console.log("Listner1 will not listen now.");
// Fire the connection event
eventEmitter.emit('connection');
eventListeners = require('events').EventEmitter.listenerCount(eventEmitter,'connection');
console.log(eventListeners + " Listner(s) listening to connection event");
console.log("Program Ended.");