ECMAScript engine A JavaScript engine is a software component that executes JavaScript code. The first JavaScript engines were mere interpreters, but all relevant modern engines use just-in-time compilation for improved performance. JavaScript engines are typica ...

is a program that executes source code written in a version of the

ECMAScript ECMAScript (; ES) is a JavaScript standard intended to ensure the interoperability of web pages across different browsers. It is standardized by Ecma International in the documenECMA-262 ECMAScript is commonly used for client-side scripting o ...

language standard, for example, JavaScript.

Just-in-time compilation engines

These are new generation ECMAScript engines for web browsers, all implementing

just-in-time compilation In computing, just-in-time (JIT) compilation (also dynamic translation or run-time compilations) is a way of executing computer code that involves compilation during execution of a program (at run time) rather than before execution. This may co ...

(JIT) or variations of that idea. The performance benefits for just-in-time compilation make it much more suitable for web applications written in JavaScript. * Carakan: A JavaScript engine developed by

Opera Software ASA Otello Corporation ASA (formerly Opera Software ASA) is a Norwegian internet company which develops advertising and mobile software for operators, publishers and advertisers. It operates through its subsidiaries which include AdColony (formerly ' ...

, included in the 10.50 release of the Opera web browser, until switching to V8 with Opera 15 (released in 2013). * Chakra (JScript9): A JScript engine used in Internet Explorer. It was first previewed at MIX 10 as part of the Internet Explorer 9 Platform Preview. *

Chakra Chakras (, ; sa , text=चक्र , translit=cakra , translit-std=IAST , lit=wheel, circle; pi, cakka) are various focal points used in a variety of ancient meditation practices, collectively denominated as Tantra, or the esoteric or ...

: A JavaScript engine previously used in older versions of Microsoft Edge, before being replaced by V8. *

SpiderMonkey SpiderMonkey is the first JavaScript engine, written by Brendan Eich at Netscape Communications, later released as open source and currently maintained by the Mozilla Foundation. It is used in the Firefox web browser. History Eich "wrote ...

: A JavaScript engine in Mozilla

Gecko Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates throughout the world. They range from . Geckos are ...

applications, including Firefox. The engine currently includes the IonMonkey compiler and OdinMonkey optimization module, has previously included the TraceMonkey compiler (first JavaScript JIT) and JägerMonkey. *

JavaScriptCore WebKit is a browser engine developed by Apple and primarily used in its Safari web browser, as well as on the iOS and iPadOS version of any web browser. WebKit is also used by the BlackBerry Browser, PlayStation consoles beginning from the ...

: A JavaScript interpreter and JIT originally derived from KJS. It is used in the WebKit project and applications such as Safari. Also known as Nitro, SquirrelFish, and SquirrelFish Extreme. * JScript .NET: A

.NET Framework The .NET Framework (pronounced as "''dot net"'') is a proprietary software framework developed by Microsoft that runs primarily on Microsoft Windows. It was the predominant implementation of the Common Language Infrastructure (CLI) until bein ...

JScript engine used in

ASP.NET ASP.NET is an open-source, server-side web-application framework designed for web development to produce dynamic web pages. It was developed by Microsoft to allow programmers to build dynamic web sites, applications and services. The name sta ...

based on Common Language Runtime and

COM Interop Com or COM may refer to: Computing * COM (hardware interface), a serial port interface on IBM PC-compatible computers * COM file, or .com file, short for "command", a file extension for an executable file in MS-DOS * .com, an Internet top-level ...

. Unfortunately support was dropped with

.NET Core The domain name net is a generic top-level domain (gTLD) used in the Domain Name System of the Internet. The name is derived from the word ''network'', indicating it was originally intended for organizations involved in networking technologies ...

and CoreCLR so its future looks questionable for

ASP.NET Core ASP.NET Core is a free and open-source web framework and successor to ASP.NET, developed by Microsoft. It is a modular framework that runs on both the full .NET Framework, on Windows, and the cross-platform .NET. However, ASP.NET Core version 3 ...

. * Tamarin: An

ActionScript ActionScript is an object-oriented programming language originally developed by Macromedia Inc. (later acquired by Adobe). It is influenced by HyperTalk, the scripting language for HyperCard. It is now an implementation of ECMAScript (meaning i ...

and ECMAScript engine used in

Adobe Flash Adobe Flash (formerly Macromedia Flash and FutureSplash) is a multimedia Computing platform, software platform used for production of Flash animation, animations, rich web applications, application software, desktop applications, mobile apps, mo ...

. * V8: A JavaScript engine used in

Google Chrome Google Chrome is a cross-platform web browser developed by Google. It was first released in 2008 for Microsoft Windows, built with free software components from Apple WebKit and Mozilla Firefox. Versions were later released for Linux, macOS, ...

and other

Chromium Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal. Chromium metal is valued for its high corrosion resistance and hardne ...

-based browsers,

Node.js Node.js is an open-source server environment. Node.js is cross-platform and runs on Windows, Linux, Unix, and macOS. Node.js is a back-end JavaScript runtime environment. Node.js runs on the V8 JavaScript Engine and executes JavaScript cod ...

, Deno, and V8.NET. * GNU Guile features an ECMAScript interpreter as of version 1.9 *

Nashorn ''Nashorn'' (, German for " rhinoceros"), initially known as ''Hornisse'' (German " hornet"), was a German ''Panzerjäger'' ("tank hunter") of World War II. It was developed as an interim solution in 1942 by equipping a light turretless chass ...

: A JavaScript engine used in Oracle Java Development Kit (JDK) since version 8. * iv, ECMAScript Lexer / Parser / Interpreter / VM / method JIT written in C++. * CL-JavaScript: Can compile JavaScript to machine language on Common Lisp implementations that compile to machine language. * BESEN: A complete JIT-compiling implementation of ECMAScript Fifth Edition written in Object Pascal. * Hermes: developed by Facebook for React Native mobile apps * Graal.js: An ECMAScript compliant JavaScript engine for

GraalVM GraalVM is a Java VM and JDK based on HotSpot/ OpenJDK, implemented in Java. It supports additional programming languages and execution modes, like ahead-of-time compilation of Java applications for fast startup and low memory footprint. The f ...

which supports language interoperability that can also execute Node.js applications.

Runtime interpreter engines

The following engines use runtime interpreters, which do not compile into native machine code and generally run more slowly: * Continuum: A self-interpreter that supports older drafts of the ECMAScript 2015 specification. Uniquely, the engine is implemented in ECMAScript 3, which made it possible to run ES2015 in browsers as old as IE6. *

Futhark Runes are the letters in a set of related alphabets known as runic alphabets native to the Germanic peoples. Runes were used to write various Germanic languages (with some exceptions) before they adopted the Latin alphabet, and for specialis ...

: The ECMAScript engine of the Opera web browser versions 9.50 to 10.10. *

InScript InScript (short for Indic Script) is the decreed standard keyboard layout for Indian scripts using a standard 104- or 105-key layout. This keyboard layout was standardised by the Government of India for inputting text in languages of India writ ...

: An obsolete

proprietary {{Short pages monitor