Node Js— An Introduction

What is Node.js?

• Node.js was developed by Ryan Dahl in 2009.
• Node.js is an open source server environment that provides server side rendering in Java Script.
• It runs on all the platforms(Windows, Linux, Unix, etc) and free to install.
• It is a JavaScript based platform that is build on google chrome V8 engine.

Node.js uses asynchronous programming!!🧐

This means it eliminates the waiting, and simply continues with the next request.

Here is how Node.js works:

1. It first sends the task-1.
2. Till the time Task-1 is executing it takes up the another task-2.
3. In this way it performs multitasking by handling multiple requests at the same time.

Synchronous vs Asynchronous

In Synchronous Programming,

The flow of request is straight that means

Task-1 will be executed and unless and until it will not complete no other task can be taken up.

Post completion of Task-1 only the second task will execute.

Synchronous Programming

👉REPL In Node JS…

REPL stand for:

1️⃣ R — Reading the user input and parsing it into JS data structure.

2️⃣ E — Eval, means evaluate the input

3️⃣ P — Print the result

4️⃣ L — Loops the command until user abort it by pressing ctrl-C twice.

REPL is a feature of Node tat provides an environment to experiment the code like we have CMD in windows.

To start Node- e write the below command in terminal:

REPL

Various operations we can perform in REPL such as Simple Expressions, Using Variables, Multiline Expressions, Underscore Variables:

👉Commands and special keys…

The following special commands are supported by all REPL instances:

• .break: When in the process of inputting a multi-line expression, enter the .break command (or press Ctrl+C) to abort further input or processing of that expression.
• .clear: Resets the REPL context to an empty object and clears any multi-line expression being input.
• .exit: Close the I/O stream, causing the REPL to exit.
• .help: Show this list of special commands.
• .save: Save the current REPL session to a file: > .save ./file/to/save.js
• .load: Load a file into the current REPL session. > .load ./file/to/load.js
• .editor: Enter editor mode (Ctrl+D to finish, Ctrl+C to cancel).

Keep Learning✌

Thank You!!😀