Answer: JavaScript is a high-level, interpreted, dynamically typed, and multi-paradigm scripting language primarily used to create interactive web applications.
It was initially designed for client-side scripting, but now it’s used for:
- Server-side development (Node.js)
- Mobile apps (React Native, Ionic)
- Desktop apps (Electron.js)
- Game development (Phaser, Three.js)
- IoT and Machine Learning
"JavaScript allows developers to build full-stack applications using the same language on both client and server sides."
Answer:
- Powers over 95% of websites
- Used by top companies like Google, Netflix, LinkedIn, Facebook, Uber
- Supported natively by all browsers
- Huge ecosystem (npm, libraries, frameworks)
- Enables full-stack development (React + Node.js)
Answer:
- Interpreted (not compiled)
- High-level and dynamic
- Prototype-based OOP
- Supports event-driven and functional programming
- Runs in browsers and server environments (like Node.js)
Answer:
- Brendan Eich created JavaScript in 1995 while working at Netscape.
- It was created in just 10 days.
Answer:
- Originally called Mocha
- Renamed to LiveScript
- Finally named JavaScript (for marketing, to ride on Java’s popularity)
Answer: JavaScript was first implemented in Netscape Navigator 2.0.
Answer: JScript was Microsoft’s reverse-engineered version of JavaScript for Internet Explorer, leading to inconsistencies in early web development.
Answer: To avoid fragmentation, JavaScript was standardized in 1997 by ECMA International, under the name ECMAScript (ES).
Answer: ECMAScript is the official standard for JavaScript defined by ECMA International (specifically the TC39 Committee).
- JavaScript is the language.
- ECMAScript is the specification.
Answer:
| Version | Year | Key Features |
|---|---|---|
| ES5 | 2009 | Strict mode, Array methods, JSON support |
| ES6 (ES2015) | 2015 | let, const, arrow functions, classes, promises, modules, template literals |
| ESNext | Ongoing | Refers to the most recent or upcoming ECMAScript proposals and updates |
Answer: A JavaScript engine is a program that parses, interprets, and executes JavaScript code.
Different browsers use different engines:
| Engine | Browser / Platform |
|---|---|
| V8 | Google Chrome, Node.js |
| SpiderMonkey | Mozilla Firefox |
| JavaScriptCore | Apple Safari |
| Chakra | Microsoft Edge (legacy) |
Answer:
- V8 is Google’s high-performance JavaScript engine written in C++.
- Used in Google Chrome and Node.js.
- It uses JIT (Just-In-Time) compilation to convert JS into machine code.
- V8 is open-source.
"V8 enabled JavaScript to perform efficiently in browsers and on servers via Node.js."
Answer:
- Node.js is not a language or a framework.
- It is a JavaScript runtime environment that runs JS code outside the browser, built on V8 Engine.
- Enables building scalable server-side applications.
- Supports event-driven, non-blocking I/O, ideal for real-time systems.
Answer:
- Executes JavaScript outside browsers
- Handles thousands of connections using non-blocking asynchronous I/O
- Uses a single-threaded event loop
- Suitable for REST APIs, microservices, real-time apps like chat
Answer:
"JavaScript started as a simple scripting language for web pages, but with ECMAScript standardization, V8 engine performance, and environments like Node.js, it evolved into a full-stack, universal programming language for the web, mobile, desktop, and more."