JavaScript

What is JavaScript?
JavaScript is a high-level , interpreted programming language used mainly to make websites interactive and dynamic.
It works along with HTML (structure) and CSS (design).
JavaScript adds behavior and functionality to web pages.
It runs directly in the web browser.

Example
showing a popup message
Hiding or showing content when a button is clicked
Validating a form before submitting

Why is JavaScript important?
JavaScript makes web pages:
Interactive -buttons,animations,pop-up messages
Smart - form validation(checking user input)
Dynamic - change text,images,content without reloading
Connected - helps fetch data from servers(APIs)

Where Does JavaScript Run?
1.In the web browser(Client-Side)
This is the most common use of JavaScript.
* Web browsers like Google Chrome,Firefox,Edge,Safari have a built-in JavaScript engine(like Chrome uses V8).
* When you open a webpage, the browser reads the HTML,CSS and Javascript.
* The JavaScript then runs directly on your computer or mobile device.
2.On the Server using Node.js(Server-Side)
JavaScript is not only for browsers! With Node.js,it can run on servers too.
* Node.js is like a special environment that allows JavaScript to run outside the browser,on a computer or server.
* It uses the same V8 engine as chrome but adds features like reading files, connecting to databases, handling requests from users,etc.

How JavaScript Works in Browser?
1.User opens a webpage
2.Browser loads HTML & CSS
3.Browser reads JavaScript and executes it
4.JavaScript interacts with HTML using DOM(Document Object Model)
5.page becomes interactive

Advantages of JavaScript
* Easy to learn
* Runs in all modern browsers
* Fast execution
* Large community support
* can be used for both frontend(browser) and backend(Node.js)

Disadvantages
* can be misused for malicious scripts
* Browser differences may cause issues
* Not secure for confidential data(runs on client-slide)