Node Programming Examples

Node.js Event driven Programming

node

// 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.");

Node.js Hello World Example

node

/* Hello, World! program in node.js */
console.log("Hello, World!")

Execute Node.js Online

node

/* Simple Hello World in Node.js */
console.log("Hello World");

base64 and string convertions

node

/* Simple Hello World in Node.js */

var resp = {};
resp.json = "{test}";
resp.html = "test";
console.log(resp);

//base64 to hex
var idStr = "Dev:Devuser@1234";
var buffer = new Buffer(idStr, 'base64');
	var toHex = buffer.toString('hex');
	console.log("Encode: " + toHex);
	
//base64 to string
var b = new Buffer('RGV2OkRldnVzZXJAMTIzNA==', 'base64')
var s = b.toString('utf8');
console.log("Decode: " +s);

//string to base64 convertion
var idStr = "Dev:Devuser@1234";
var buffer = new Buffer(idStr, 'utf8');
	var toHex = buffer.toString('base64');
	console.log("Encode: " + toHex);

fvxcvxc

node

/* Simple Hello World in Node.js */
console.log("Hello World!!!");

aaaa

node

/* Simple Hello World in Node.js */
console.log("Hello World");

hello

node

/* Simple Hello World in Node.js */
console.log("Hello World");

String Replaces in JS

node

/* Simple Hello World in Node.js */

var testStr = "going again to modifiy going again";
//var repStr = testStr.replace(/going/gi, "coming");
var rs1 = "going";
var rep_regex = new RegExp(rs1,"gi");
var str_rep = testStr.replace(rep_regex,"devaraj");

console.log(str_rep);

test

node

const http = require('http')
const port = 3000

const requestHandler = (request, response) => {
  console.log(request.url)
  response.end('Hello Node.js Server!')
}

const server = http.createServer(requestHandler)

server.listen(port, (err) => {
  if (err) {
    return console.log('something bad happened', err)
  }

  console.log(`server is listening on ${port}`)
})

Execute Node.js Online

node

var http=require('http');
    
http.createServer(function(req,res){
    res.writeHead(200);
    res.end("hai");
}).listen(8081);
console.log("8081");

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