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Ezhil Arasan
Ezhil Arasan

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Java Script

What Can JavaScript Do?
JavaScript is the programming language of the web.
It can calculate, manipulate and validate data.
It can update and change both HTML and CSS.

JavaScript Can Change HTML Content
One of many JavaScript HTML methods is getElementById().
The example below "finds" an HTML element (with id="demo"), and changes the element content (innerHTML) to "Hello JavaScript":

JavaScript in <head> or <body>

You can place any number of scripts in an HTML document.
Scripts can be placed in the <body>, or in the<head> section of an HTML page, or in both.

JavaScript in <head>

In this example, a JavaScript function is placed in the <head> section of an HTML page.

The function is invoked (called) when a button is clicked:

<!DOCTYPE html>
<html>
<head>
<script>
function myFunction() {
  document.getElementById("demo").innerHTML = "Paragraph changed.";
}
</script>
</head>
<body>

<h2>Demo JavaScript in Head</h2>

<p id="demo">A Paragraph</p>
<button type="button" onclick="myFunction()">Try it</button>

</body>
</html>
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JavaScript in <body>

In this example, a JavaScript function is placed in the <body> section of an HTML page.

The function is invoked (called) when a button is clicked:

 <!DOCTYPE html>
<html>
<body>

<h2>Demo JavaScript in Body</h2>

<p id="demo">A Paragraph</p>

<button type="button" onclick="myFunction()">Try it</button>

<script>
function myFunction() {
  document.getElementById("demo").innerHTML = "Paragraph changed.";
}
</script>

</body>
</html>
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Java script
JavaScript is a programming language used to create dynamic content for websites. It is a lightweight, cross-platform, and single-threaded programming language. It's an interpreted language that executes code line by line, providing more flexibility.
Client Side: On the client side, JavaScript works along with HTML and CSS. HTML adds structure to a web page, CSS styles it, and JavaScript brings it to life by allowing users to interact with elements on the page, such as actions on clicking buttons, filling out forms, and showing animations. JavaScript on the client side is directly executed in the user's browser.
Server Side: On the Server side (on Web Servers), JavaScript is used to access databases, file handling, and security features to send responses, to browsers.

Why Learn JavaScript?
1) Core language for web development, enabling dynamic and interactive features in websites with fewer lines of code.
2) Highly in demand, offering many job opportunities in Frontend, Backend (Node.js), and Full Stack Development.
3) Supports powerful frameworks and libraries like React, Angular, Vue.js, Node.js, and Express.js, widely used in modern web applications.
4) Object-oriented and event-driven language, ideal for building scalable and responsive applications.
5) Cross-platform and runs directly in all modern web browsers without the need for installation.
6) Major companies like Google, Facebook, and Amazon use JavaScript in their tech stacks.

JavaScript Hello World Program

Mostly browsers can run JavaScript directly, so there's no need to install a compiler. However, the built-in browser console isn’t very beginner-friendly. That’s why we’ve added an online editor below to help you get started easily.

console.log("Hello World!");
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Refrence
https://www.geeksforgeeks.org/javascript/variables-datatypes-javascript/
https://www.w3schools.com/js/js_whereto.asp

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