Node Programming Examples

Node.js Console

node

console.info("Program Started");

var counter = 10;
console.log("Counter: %d", counter);

console.time("Getting data");
//
// Do some processing here...
// 
console.timeEnd('Getting data');

console.info("Program Ended")

Node.js setInterval

node

function printHello() {
   console.log( "Hello, World!");
}

// Now call above function after 2 seconds
setInterval(printHello, 2000);

Node.js Clear Timeout

node

function printHello() {
   console.log( "Hello, World!");
}

// Now call above function after 2 seconds
var t = setTimeout(printHello, 2000);

// Now clear the timer
clearTimeout(t);

Node.js Settimeout

node

function printHello() {
   console.log( "Hello, World!");
}

// Now call above function after 2 seconds
setTimeout(printHello, 2000);

Node.js Global Object Dirname

node

// Let's try to print the value of __dirname

console.log( __dirname );

Node.js Global Object File name

node

// Let's try to print the value of __filename

console.log( __filename );

Node.js Writing a file

node

var fs = require("fs");

console.log("Going to write into existing file");
fs.writeFile('input.txt', 'Simply Easy Learning!', function(err) {
   if (err) {
      return console.error(err);
   }
   
   console.log("Data written successfully!");
   console.log("Let's read newly written data");
   fs.readFile('input.txt', function (err, data) {
      if (err) {
         return console.error(err);
      }
      console.log("Asynchronous read: " + data.toString());
   });
});

Node.js Decompressed Stream

node

var fs = require("fs");
var zlib = require('zlib');

// Decompress the file input.txt.gz to input.txt
fs.createReadStream('input.txt.gz')
   .pipe(zlib.createGunzip())
   .pipe(fs.createWriteStream('input.txt'));
  
console.log("File Decompressed.");

Node.js Chaining Stream

node

var fs = require("fs");
var zlib = require('zlib');

// Compress the file input.txt to input.txt.gz
fs.createReadStream('input.txt')
   .pipe(zlib.createGzip())
   .pipe(fs.createWriteStream('input.txt.gz'));
  
console.log("File Compressed.");

Node.js Piping Stream

node

var fs = require("fs");

// Create a readable stream
var readerStream = fs.createReadStream('input.txt');

// Create a writable stream
var writerStream = fs.createWriteStream('output.txt');

// Pipe the read and write operations
// read input.txt and write data to output.txt
readerStream.pipe(writerStream);

console.log("Program Ended");

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