Callback Function in Node.js

A callback function is a function which can be passed as an argument into another function. This callback function can then be invoked inside the outer function. Callback functions were introduced in JavaScript. Since Node.js built on V8 engine, it also support callback functions. In the above example, doComplete is a callback function. This program … Read more Callback Function in Node.js

Basic web application in Node.js to return text

Here we write a basic web application in Node.js that serves static text to the client’s HTTP requests. Added an event listener on the server variable that listens to the request events. The event listener takes a callback function with two arguments, request and response. If there is a request, node.js will raise a request … Read more Basic web application in Node.js to return text

Why does a while loop blocks the event loop?

How Node.js process this program? flag variable declaration will be placed in call stack and it will be initialized to true. setTimeout() function call will be placed in call stack. Node.js start the timer and schedules a timer event for 1 second. The callback function will be placed in MessageQueue after 1 second. Node.js continues … Read more Why does a while loop blocks the event loop?

Read File Synchronously and Asynchronously (Blocking and Non-blocking ways)

In this post we will learn to read a text file synchronously with a blocking code and asynchronously by writing non-blocking code. Node.js provides methods to read a file both synchronously and asynchronously in it’s ‘fs’ module. Synchronously reading a file using blocking methods of Node.js: Asynchronously reading a file using non-blocking methods of Node.js:

Simple Web Server Program in Node.js

Here we write a simple web server program in Node.js that serves static text to the client’s HTTP requests. The createServer method returns a http.Server object We are passing requestListener callback function as a parameter to createServer which automatically added to the ‘request’ event http.Server emits ‘request’ event when it receives a request The request … Read more Simple Web Server Program in Node.js

Piping Readable Stream to Writable Stream

In this post you’ll learn how to pipe readable stream into writable stream. Piping readable stream to standard output Line 1: Importing ‘request’ module which simplifies reading from http request. Make sure to download this module using npm install request Line 2: Requesting response from a web address Line 3: Piping the readable stream to … Read more Piping Readable Stream to Writable Stream