What is JavaScript?

Introduction

JavaScript is a versatile programming language that powers much of the interactive web we use daily. If you're beginning your coding journey and want to learn JavaScript, you've chosen one of the most widely used languages with endless opportunities for creating dynamic web experiences.

Technically, JavaScript is a high-level, dynamically-typed, interpreted programming language that runs in browsers and Node.js environments. It stands out for its universal role in web development, event-driven architecture, and asynchronous programming model.

History of JavaScript

JavaScript was created in just 10 days in May 1995 by Brendan Eich while working at Netscape Communications. Originally called "Mocha", then briefly "LiveScript", it was finally named "JavaScript" as a marketing move to capitalize on the popularity of Java (though the two languages are quite different).

Although the term “JavaScript” is trademarked by Oracle, the language is driven by the standard specification known as ECMAScript. Features and behavior of the language are decided by a technical committee named TC39, where a number of tech companies participate to ensure standardization.

Key historical milestones include its standardization as ECMAScript in 1996, which ensured cross-browser compatibility. After a period of slower development, ECMAScript 5 (ES5) arrived in 2009 with important improvements. Then ECMAScript 2015 (ES6) marked a significant evolution, introducing major enhancements such as arrow functions, classes, and modules.

Since 2015, annual releases have continued to evolve the language, with ECMAScript 2024 (ES15) being the current iteration.

Purpose of JavaScript

JavaScript was initially designed to make web pages interactive. Today, its purpose has expanded significantly:

• Client-side web development: Adding dynamic behavior to websites
• Server-side development: Running back-end services with Node.js
• Mobile app development: Creating native-like apps using frameworks like React Native
• Desktop application development: Building cross-platform apps with Electron

This tutorial resource particularly focuses on the web development aspect of JavaScript.

JavaScript's Role in Web Development

JavaScript forms one of the three core technologies of web development:

• HTML: Provides the structure of web pages
• CSS: Controls the presentation and styling
• JavaScript: Adds behavior and interactivity

In modern web development, JavaScript's role includes DOM Manipulation (changing page content dynamically), Event Handling (responding to user actions like clicks), and Asynchronous Operations like AJAX for loading data without refreshing the page.

It's also used for creating smooth Animation, Form Validation before submission, and building Single Page Applications (SPAs) that load once and update dynamically.

Why Learn JavaScript?

JavaScript (or JS) is one of the cores of the web, and every web developer needs to learn it. By visiting this page, you've already taken the first step!

Beyond its fundamental role, there's consistently high demand for JavaScript developers. The language runs on virtually every device with a web browser and can be used in front-end, back-end, mobile, and desktop development.

It's a mature language with vast resources, libraries, and community support, and it begins with simple concepts, allowing for gradual learning.

JavaScript Engine

JS code gets executed in JavaScript engines present in web browsers, and the most used one is Google's V8 engine for Chromium. As the majority of browsers today are chromium-based, it’s essential that your code runs well here.

The V8 engine uses Just-In-Time (JIT) compilation, converting JavaScript into optimized machine code at runtime, and features like garbage collection for automatic memory management. It's constantly improved for better performance.

Other notable engines include SpiderMonkey (Firefox) and JavaScriptCore (Safari). Microsoft Edge, which previously used its own Chakra engine, transitioned to the V8 Engine (Chromium) in 2021.

Modern JavaScript Ecosystem

JavaScript's ecosystem has grown tremendously; here are some names you may have heard about:

• Frameworks and Libraries: React, Angular, Vue.js, jQuery
• Package Management: npm, yarn
• Build Tools: Vite, Webpack, Babel
• Testing Frameworks: Jest, Mocha, Jasmine
• Supersets: TypeScript (adds static typing to JavaScript)

Getting Started

As a beginner, you'll start with JavaScript fundamentals like variables, data types, functions, and control flow before moving to more advanced concepts. The language is designed to be accessible, with immediate feedback when running code in a browser.

Remember, every expert JavaScript developer started exactly where you are now!