Node JS

Node JS is a runtime enviroment to run javascript files in the terminal

Here there is no window object, but we have different objects here, like global

Process

    This object provides information about, and control over, the current Node.js process.

    * process.argv returns an array of the arguments passed while running the code.

Module Exports

Transfering Data within the same directory

    * module.exports = what you want to export

    * This exported data need to be imported using the require method. Example: 
    const someVal = require("./math")

    * module.export only exports one this at a time, so we can send multiple things using the export by combining them into a object.

    * We can also export by using 
        exports.var_name; (we can even give defination here too)

importing and exporting

We need to use the export keyword in the parent file. Example: export const a =5;

This exported data can be imported using:
    import {what you need to import} from "filepath"

    But make sure to add type:"module" in package.json

Transfering data within different directories

    * We need to collect the data which we need to export into index.js file in that directory

    * Then we need to pass the address of that directory in the require function (don't pass the file name)

    * The require function searches for index.js and imports that

Node Package Manager (npm)

* npm is the standard package manager for Node.js

* it allows us to install packages from a large library

* it is a command line tool

* installing packages: npm install package_name

* local installation: npm by defaults installs the packages locally.

* global installation

    use npm install -g package_name (but the terminal should have admin rights)

    inorder to import these package we need to use npm link package_name

* node_modules: This directory contains every installed dependency/packages of your project

* package-lock.json : It records the exact version of every installed dependency, including its sub-dependencies and their versions.

* package.json 
    The package.json contains all the information about your project, such as name, dependecies required to run, version.

    We don't need to push node_modules or package-lock.json because they can be installed using package.json file.

Library VS Framework

Both are prebuilt codes but library provides tools for some specific purpose but frameworks provides the overall structure.