Javascript Advanced: Introduction to Javascript Engine

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Javascript Engine

A JavaScript engine is a piece of software that executes JavaScript code. The initial JavaScript engines were simply interpreters, but for enhanced performance, all significant current engines use just-in-time compilation.

Web browser companies typically build JavaScript engines, and every major browser includes one. The JavaScript engine collaborates with the rendering engine in a browser via the Document Object Model.

JavaScript engines are used in applications other than browsers. The V8 engine, for example, is a key component of the Node.js and Deno runtime systems.

Because ECMAScript is the standardized specification for JavaScript, these engines are also known as ECMAScript engines. Some engines can now execute this code in the same sandbox as conventional JavaScript code thanks to the introduction of WebAssembly.

The articles in this JabaScript Advanced series are listed below.

JavaScript Engines List:

BrowserName of Javascript Engine
Google ChromeV8
Mozilla FirefoxSpider Monkey
SafariJavascript Core Webkit

V8 Engine

The Chromium Project’s V8 JavaScript engine is designed for Google Chrome and Chromium web browsers. It is a JavaScript engine that may operate independently or as part of any C++ application. It produces an abstract syntax tree using its own parser. The internal V8 bytecode format is then used by Ignition to generate bytecode from this syntax tree. TurboFan converts bytecode to machine code. It also handles object memory allocation and garbage collection for things that are no longer needed. Techniques for optimization include the removal of costly runtime attributes and inline caching. The garbage collector works in a generational, incremental fashion.

Spider Monkey

SpiderMonkey was the original JavaScript engine, built by Brendan Eich at Netscape Communications, and is now maintained by the Mozilla Foundation. It is still used in the web browser Firefox.

Javascript Core Webkit

Apple created WebKit, which is used in the Safari web browser as well as all iOS web browsers. It is used by the BlackBerry Browser, PlayStation consoles beginning with the PS3, Tizen mobile operating systems, and an Amazon Kindle e-book reader browser. WebKit’s C++ application programming interface (API) includes a set of classes for displaying Web content in windows and implementing browser functionality such as following links when the user clicks them, managing a back-forward list, and managing a history of recently viewed pages.


Microsoft created the Chakra JScript engine. It’s a piece of proprietary software. It is used in the web browser Internet Explorer. The engine is notable for JIT compiling scripts on a second CPU core, simultaneous to the web browser.

The Javascript Runtime Environment

What exactly is a runtime environment?

Your software will be executed in a runtime environment. It determines which global items your application may access, as well as how it operates. This article discusses both JavaScript runtime environments:

  1. A browser’s runtime environment (like Chrome, or Firefox)
  2. The environment in which Node runs

The Runtime Environment of a Browser

A browser is the most common site where JavaScript code is run. For example, you might use any text editor to create a file on your computer named my website.html and insert the following HTML code inside: