JavaScript

Last Updated : 19 Oct, 2022

JavaScript is the world’s most popular lightweight, interpreted compiled programming language. It is also known as scripting language for web pages. It can be used for Client-side as well as Server-side developments.

JavaScript Tutorial

JavaScript can be added to your HTML file in two ways:

Internal JavaScript: We can add JavaScript code directly to our HTML file by writing the code inside the <script> tag. The <script> tag can either be placed inside the <head> or the <body> tag according to the requirement.
External JavaScript File: We can create a file with .js extension and paste the JavaScript code inside it. After creating the file, add this file in <script src=”file_name.js”> tag inside <head> tag of the HTML file.

Syntax:

<script>
    // JavaScript Code
</script>

Example 1: It is the basic example of JavaScript code embedded in HTML file.

<!DOCTYPE html>
<html lang="en">

<head>
    <title>
        Basic Example to Describe JavaScript
    </title>
</head>

<body>

    <!-- JavaScript code can be embedded inside
        head section or body section -->
    <script>
        console.log("Welcome to GeeksforGeeks");
    </script>
</body>

</html>

Output: The output will display on console.

Welcome to GeeksforGeeks

Example 2: In this example, we will make a simple function and print the values.

JavaScript

<script>
 
    // Declare a variable and initialize it
    // Global variable declaration
    var Name = "Apple";
 
    // Function definition
    function MyFunction() {
 
        // Local variable declaration
        var num = 45;
 
        // Console value of Gloabal variable
        console.log(Name);
 
        // Console value of local variable
        console.log("\n" + num);
    }
     
    // Function call
    MyFunction();
</script>

Output: Console output

Apple
45

How JavaScript is different from HTML?

JavaScript is an advanced programming language that makes web pages more interactive and dynamic whereas HTML is a standard markup language that provides the primary structure of a website.
JavaScript simply adds dynamic content to websites to make them look good and HTML work on the look of the website without the interactive effects and all.
JavaScript manipulates the content to create dynamic web pages whereas HTML pages are static which means the content cannot be changed.
JavaScript is not cross-browser compatible whereas HTML is cross-browser compatible.
JavaScript can be embedded inside HTML but HTML can not be embedded inside JavaScript.

Why JavaScript is used?

Web pages with interactive elements: User interaction with web pages is enabled through JavaScript. On a web page, JavaScript has essentially no bounds.
Developing online and mobile applications: For web and mobile app development, developers can employ a variety of JavaScript frameworks.
Creating web servers and server applications: Aside from websites and apps, developers may use JavaScript to create simple web servers and Node.js to construct backend infrastructure.
Game Development: Browser games can also be made using JavaScript. Beginning developers can use these to hone their JavaScript skills.

Is JavaScript easy to learn?

In comparison to other programming languages such as C++, Ruby, and Python, JavaScript is simple and easy to learn. The difficulty of learning JavaScript is primarily determined by your knowledge of other programming languages. Understanding HTML is the first step toward learning JavaScript. Because JavaScript is most commonly used as part of a web page, which can only be learned through HTML.

What can we build using JavaScript ?

JavaScript is a widely-used programming language. Given below are some domains/products that can be built using JavaScript:

Websites: JavaScript helps us to add behavior of our website. It helps users to interact with the website. For eg. clicking on buttons, saving details, uploading details on the website, etc.
Web Servers: We can make robust server applications using JavaScript. To be precise we use JavaScript frameworks like Node.js and Express.js to build these servers.
Game Development: In Game Development industry, JavaScript is used widely. With the addition of HTML5 Canvas, it’s now possible to make 2D and 3D games in JavaScript very efficiently.
3D Drawings: JavaScript in addition with HTML Canvas is used to make three-dimensional graphics.
Mobile Apps: Mobile applications are the most popular modes of communicating these days. JavaScript also used to design mobile applications. There are many JavaScript frameworks using which we can make android, IOS, and hybrid apps.
Smartwatch Apps: The popular smartwatch maker Pebble has created Pebble.js, a small JavaScript framework that allows a developer to create an application for the Pebble line of watches in JavaScript.

Why to learn JavaScript ?

JavaScript is the most popular and hence the most loved language around the globe. Apart from this, there are abundant reasons to learn it. Below are a listing of few important points:

No need of compilers: Since JavaScript is an interpreted language, therefore it does not need any compiler for compilations.
Used both Client and Server-side: Earlier JavaScript was used to build client-side applications only, but with the evolution of its frameworks namely Node.js and Express.js, it is now widely used for building server-side applications too.
Helps to build a complete solution: As we saw, JavaScript is widely used in both client and server-side applications, therefore it helps us to build an end-to-end solution to a given problem.
Used everywhere: JavaScript is so loved because it can be used anywhere. It can be used to develop websites, games or mobile apps, etc.
Huge community support: JavaScript has a huge community of users and mentors who love this language and take it’s legacy forward.

Learn more about JavaScript:

JavaScript Complete References:

JavaScript Interview Questions:

JavaScript Practice Quiz:

JavaScript Examples: Please go through this link to see the wide collection of JavaScript programming examples. The examples are categorized based on the topics, including objects, functions, arrays, DOM, and many more.

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