Javascript in 100s

JavaScript: A High-Level, Single-Threaded, Multi-Paradigm Language

JavaScript is a high-level, single-threaded, garbage-collected, interpreted, or just-in-time (JIT) compiled, prototype-based, multi-paradigm, and dynamic language with a non-blocking event loop. It is most famous for building websites and has become one of the most essential technologies in the web development world.

Brief History

JavaScript was created in 1995 by Brendan Eich in just one week, with the goal of adding an easy-to-learn scripting language to the Netscape browser. Initially, it was called "Mocha," but in a marketing effort to capitalize on the popularity of Java, it was renamed JavaScript, even though the two languages are quite different. Despite the rushed development, JavaScript has evolved into a robust, feature-rich language, governed by the ECMAScript standard (often abbreviated as ES).

What Makes JavaScript Unique?

High-Level and Dynamic

JavaScript operates at a high level, abstracting away many of the complexities of lower-level languages like memory management. Being dynamic, it allows variables to change types and structures during runtime, adding flexibility to the language.

Single-Threaded with Non-Blocking Event Loop

Although JavaScript is single-threaded (it executes one instruction at a time), it’s highly effective in handling asynchronous operations thanks to its non-blocking event loop. The event loop enables JavaScript to queue up tasks like I/O operations (file reads, network requests) and continue executing other code without waiting for those tasks to complete.

Interpreted or Just-In-Time (JIT) Compiled

JavaScript is traditionally an interpreted scripting language, meaning its code is executed directly without prior compilation. However, with modern engines like V8 (used in Google Chrome) and Node.js, JavaScript benefits from just-in-time (JIT) compilation. JIT compilation converts the code to machine code at runtime, significantly boosting performance.

Multi-Paradigm Language

JavaScript supports multiple programming paradigms, making it highly versatile. Here are the main paradigms it embraces:

• Imperative programming (procedural): Writing code with explicit statements and control structures like for loops.
• Functional programming: Functions are treated as first-class objects, which means they can be passed as arguments, returned by other functions, and assigned to variables.
• Object-oriented programming (OOP): Although JavaScript is prototype-based (objects inherit directly from other objects), it supports classes and inheritance through ES6 classes for traditional OOP patterns.

JavaScript and the Web

JavaScript is synonymous with front-end web development. It is the only language natively supported by web browsers (besides WebAssembly), which makes it crucial for creating interactive web applications.

DOM Manipulation

One of JavaScript's key roles in the browser is manipulating the Document Object Model (DOM). With the method document.querySelector, you can grab HTML elements like buttons or input fields and interact with them dynamically.

const button = document.querySelector('button');

Once you've selected an element, you can modify its behavior by adding event listeners. For example, making a button interactive:

button.addEventListener('click', () => {
  console.log('Button clicked!');
});

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