JavaScript

Computers use special code to work. This code helps websites move and change. It can make games on your screen. It also makes pictures move. It helps us use the web.

One special code is called JavaScript. A man named Brendan Eich made it. Most websites use it today. It helps pages do many things.

It can show new things without a reload. It can also play videos. It makes small boxes pop up on the screen.

This code works inside your web browser. The browser has a special tool to run it. This tool is called an engine.

People use this code for many apps too. It is a very busy tool. Do you like playing web games?

JavaScript is a special code used to make the web work. Brendan Eich created it in 1995. Today, almost all websites use it. It helps pages act in many ways.

In the past, web pages were static. This means they did not change much. JavaScript lets pages be dynamic. This means they can move or react. It can play games in your browser. It can also make animations. It can even load new data without a full page reload. This is often called Ajax.

Your web browser has a tool to run this code. We call this tool a JavaScript engine. These engines follow rules called ECMAScript. This keeps the code the same for everyone.

JavaScript is not just for browsers anymore. A system called Node.js lets people use it in other places. This helps make apps and servers. Many people use libraries to help them write code. A library is a collection of ready-to-use tools. jQuery is a very popular library. Some people write code without any tools. They call this "Vanilla JS."

JavaScript is a core technology used to build the modern web. It works alongside HTML and CSS to make websites interactive. Without it, most web pages would be static and unchanging. Instead, JavaScript allows for dynamic behavior that reacts to what you do. Today, an overwhelming 98.9% of websites use it for client-side behavior. This means the code runs right on your computer or phone. It handles things like animations, playing games, and controlling video playback.

To work, JavaScript relies on a special tool called a JavaScript engine. This engine is built into your web browser to run the code. The engine follows a set of rules called the ECMAScript standard. This standard ensures that code works the same way across different browsers. The engine processes messages one at a time from a queue. It uses a call stack to manage functions and their local variables. As each task finishes, the stack shrinks until the next message is ready.

The history of JavaScript began at the Netscape corporation in 1995. Before this, web pages could not change after they loaded. Netscape wanted a "language for the masses" to help people create interactive sites. A developer named Brendan Eich created the language. It was first called LiveScript in September 1995. Netscape changed the name to JavaScript in December of that year. They chose the name as a marketing ploy because Java was very popular then.

In the late 1990s, a "browser war" began between Netscape and Microsoft. Microsoft released its own version called JScript in 1996. Because the two versions were different, making websites work on both was hard. By the early 2000s, Internet Explorer held 95% of the market. This dominance caused the development of the language to slow down for a while. However, the release of the Firefox browser in 2004 helped change things. Later, Google released the Chrome browser in 2008 with a very fast engine.

JavaScript is no longer just for web browsers. In 2009, Ryan Dahl created Node.js to use JavaScript in other places. This allows the language to work on servers and in many different apps. Many developers also use libraries, which are collections of ready-to-use tools. jQuery is one of the most famous libraries used today. Some people prefer to write code using only standard features. They call this approach "Vanilla JS."

JavaScript is a fundamental programming language and a core technology of the modern web. It works alongside HTML and CSS to build interactive digital experiences. While HTML provides structure and CSS handles styling, JavaScript enables dynamic behavior. This allows web pages to react to user inputs without needing to reload the entire page. As of 2025, an overwhelming 98.9% of websites use JavaScript for client-side behavior. This means the code runs directly on the user's device, such as a computer or a smartphone.

To function, JavaScript requires a specialized tool called a JavaScript engine. This engine is embedded within a runtime system, such as a web browser or a standalone environment. The engine follows the ECMAScript standard, which is a set of rules ensuring the language works consistently across different platforms. JavaScript is a single-threaded language, meaning it processes one task at a time. It uses a message queue to hold tasks and a call stack to manage functions. When a function is called, a frame is added to the stack with its local variables. Once the function finishes, the stack shrinks, and the engine moves to the next message in the queue.

JavaScript is a highly flexible, multi-paradigm language. It supports various programming styles, including event-driven, functional, and imperative programming. It is characterized by dynamic typing, where variable types are determined during execution. It also uses prototype-based object-orientation and treats functions as first-class citizens. To perform specific tasks, JavaScript uses Application Programming Interfaces, or APIs. These APIs allow the language to interact with text, dates, and the Document Object Model (DOM), which represents the structure of a web page. While the ECMAScript standard defines the language logic, the runtime system provides APIs for input/output (I/O) tasks like networking, storage, and graphics.

The history of JavaScript began at Netscape in 1995. Before this time, web pages were static and could not change once they loaded. Netscape developers wanted a "language for the masses" to help nonprogrammers create interactive sites. Brendan Eich created the language, which was initially called LiveScript in September 1995. By December 1995, Netscape changed the name to JavaScript. This was a marketing decision intended to capitalize on the popularity of the Java language. Despite the similar names, Java and JavaScript are distinct languages with very different designs.

A period of intense competition known as the "browser war" followed. Microsoft released Internet Explorer in 1995 and developed its own version of the language called JScript. Because the implementations in Netscape Navigator and Internet Explorer were different, developers struggled to make websites work on both. By the early 2000s, Microsoft's Internet Explorer held a 95% market share. This dominance caused the standardization of the language to stall, and the proposed ECMAScript 4 specification was eventually mothballed. Progress resumed in 2004 with the release of the Firefox browser by Mozilla, which helped break the market monopoly.

A major turning point occurred in 2005 when Jesse James Garrett coined the term Ajax. This described a method of using JavaScript to load data in the background, preventing full page reloads. This sparked a renaissance, leading to the creation of popular libraries like jQuery, Prototype, and Dojo Toolkit. In 2008, Google released the Chrome browser featuring the V8 engine. The V8 engine introduced just-in-time (JIT) compilation, which compiles code during execution to increase speed. This innovation forced other browser vendors to overhaul their own engines to remain competitive.

In 2009, Ryan Dahl created Node.js, which expanded JavaScript's reach far beyond the browser. Node.js combines the V8 engine with an event loop and I/O APIs to create a standalone runtime system. This allowed JavaScript to be used on servers and in many non-browser applications. Today, JavaScript is used in diverse environments, from Adobe Acrobat scripting to GNOME Shell extensions. The ecosystem is vast, with over 80% of websites using third-party libraries or frameworks like React, Angular, or Vue. Even those who use only standard functionality refer to their work as "Vanilla JS."