Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient. Node.js' package ecosystem, npm, is the largest ecosystem of open source libraries in the world.

Let's break it down.

  • JavaScript runtime built on Google Chrome's V8 JavaScript engine.
    Every browser has a JavaSript engine built in it to process JavaScript files contained in websites. Chrome uses V8, which is built using C++. Node.js also uses this super-fast engine to interpret JavaScript files.
  • Node.js uses an event-driven model.
    This means that Node.js waits for certain events to take place. It then acts on those events. Events can be anything from a click to a HTTP request. We can also declare our own custom events and make node.js listen for those events.
  • Node.js uses a non-blocking I/O model.
    We know that I/O tasks take much longer than processing tasks. Node.js uses callback functions to handle such requests.

Let us assume that a particular I/O task takes 5 secs to execute. And we want to perform this I/O twice in our code.


import time

def my_io_task():



function my_io_task() {
    setTimeout(function() {
    }, 5000);


Both look similar but the time taken to execute are different. The python code takes 10 seconds to execute while the Node.js code takes only 5 seconds to execute.

Node.js takes less time because of its non-blocking I/O model. The first call to my_io_task() starts the timer and leaves it there. It does not wait for the response from the function, instead, it moves on to call the second my_io_task(), starts the timer and leaves it there.

When the timer completes it's execution taking 5 seconds, it calls the function and prints done on the console. Since, both the timers are started together, they complete together and therefore take same amount of time.


NPM is the default package manager for JavaScript runtime environment NodeJS. For more visit : NPM official site

Why use NodeJS:

  1. Great for beginners. JavaScript is a beginner friendly language.
  2. Great supportive community and massive amount of modules (Express, Grunt, etc).
  3. Wide range of hosting options.
  4. Existing Front-End developers get to transfer existing JavaScript knowledge for an easier transition into Server-Side development

More information:

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