 Dear students, now we will start a new topic which is JavaScript JavaScript is widely used and it has an important role in web development Let's have a look at how JavaScript works for us It is very important for you to understand how JavaScript works and what it does Till the time you don't have clarity, you won't be able to use JavaScript in the right way When we have a user who opens a website, he will send a get request to a page called lexivocation.html This request will be sent to web server What will the web server do? It is against HTML content And if there is a JavaScript in it, it will send that file to the client side Now this JavaScript will be in the browser And whatever work it has to do, the JavaScript which we have in the HTML page We have it in the user, it will be on the client side And whatever functionality it has to perform, it has to be done on the client side At first, we only had JavaScript for validation or functionality You still have to keep in mind that whatever work you are taking from JavaScript It will only do what you see on the page That means that while staying there, you cannot perform any functionality of the server By default, you cannot If you have to fetch data from the server side or perform any action For that, you will have to use AJAX or WebFockets So, when you execute JavaScript on the client side It will remain on the browser, the user's browser And whatever you see in the browser, it will only use the action there You can use it for layouts, for validation, for validation You can use it for drop-downs, for menu bars Let us have a look on the history of JavaScript It was initiated by Netscape Which was one of the early browsers And in 1996, it was launched Like the name of JavaScript, JavaScript is a very low-overlap of syntax Otherwise, its execution or functionality And the purposes are completely different from Java The standards of JavaScript are defined by an organization And it publishes those scripting standards, language standards Which we call ECMAScript So, JavaScript conforms to that It is not necessary that the functionality of ECMAScript Is implemented in 100% browsers It matches 100% with that Some functionality is additional in JavaScript Which is not in ECMAScript Some things can be in ECMAScript So, ECMAScript is not implemented in old browsers ECMAScript is produced by its various variants ECMAScript, which was a major variant in 2015 It was published by ES6 From 2015 onwards, ECMAScript is launched Like the script launched in 2021 ECMAScript will be launched in 2021 And if it is seen as a release It would be the 12th edition of ECMAScript When we first launched JavaScript Let's say we talk about pre-2000 It had very little usage Many people used it Developers used it The revolution in JavaScript Was used in early 2000s To fetch data from the server We call it AGX Asynchronous, JavaScript and XML It is used as an acronym And AGX is used as a word What happened with AGX We can communicate with the server If you don't use AGX You can only access the client-side resources Not all the resources You can only access the server If you want to access the server You have to use AGX Due to AGX, we have a web development And a revolution And we have a web 2.2 platform There is a major role in JavaScript And especially post AGX You will have a lot of creative scenarios And use cases You will have a lot of different sites And applications With this, you have a kind of Once you load the web page And send it to the client-side And then the refresh on the client-side There is also a new information Through the request of AGX You will obtain it from the server-side JavaScript is not used only in web development JavaScript has a lot of different applications So let's have a look at some of them You use JavaScript To create browser extensions Like you have to create Chrome's Firefox extensions You will create extensions in JavaScript Apart from this, you have non-browser applications You also have JavaScript JavaScript is commonly used in the Internet of Things And you have to develop in the Internet of Things JavaScript can help you a lot Similarly, you have embedded systems You have Raspberry Pi Or you have embedded systems You have the functionality of JavaScript You can implement your logic in JavaScript We have a lot of non-relational databases In which we have JavaScript used Like MongoDB In which you have JavaScript for queries And for other purposes Apart from this, we can create applications In JavaScript That can be run in the browser Means the entire application will be run in the browser One revolution we have in web development Was that To use JavaScript as a server-side language After 2010 I don't remember the exact year What was done was that The engine of JavaScript Which is used in Chrome It was run outside the browser When it was run outside the browser You have JavaScript It will start executing outside the browser When it is executed outside You can use it for server-side development Nowadays, you have a lot of development It is in Node.js And the programming language in Node.js That is JavaScript Apart from this, there are many other applications Like if you are programming in any other programming language You can trans-compile it into JavaScript It will convert to JavaScript With JavaScript Literally, you would find countless frameworks and libraries Which are written in JavaScript And which support JavaScript development You will get many libraries Which are popular, like front-end You have frameworks, React, View Apart from this, you have JavaScript You also have libraries Like you have jQuery You facilitate it in programming With JavaScript development It becomes very easy And in this way, you can develop All the mobile applications That you are developing You can develop them in JavaScript You will see that If you learn JavaScript well Not only will it help you in web development Apart from this, there are many other areas Where you can help out JavaScript