An ECMAScript engine 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 JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of websites use JavaScript on the client side for webpage behavior, of ...

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

. * Carakan: A JavaScript engine developed by Opera Software ASA, included in the 10.50 release of the

Opera Opera is a form of theatre in which music is a fundamental component and dramatic roles are taken by singers. Such a "work" (the literal translation of the Italian word "opera") is typically a collaboration between a composer and a libr ...

web browser, until switching to V8 with Opera 15 (released in 2013). * Chakra (JScript9): A

JScript JScript is Microsoft's legacy dialect of the ECMAScript standard that is used in Microsoft's Internet Explorer 11 and older. JScript is implemented as an Active Scripting engine. This means that it can be "plugged in" to OLE Automation applic ...

engine used in

Internet Explorer Internet Explorer (formerly Microsoft Internet Explorer and Windows Internet Explorer, commonly abbreviated IE or MSIE) is a series of graphical web browsers developed by Microsoft which was used in the Windows line of operating systems ( ...

. It was first previewed at MIX 10 as part of the Internet Explorer 9 Platform Preview. * Chakra: A

engine previously used in older versions of

Microsoft Edge Microsoft Edge is a proprietary, cross-platform web browser created by Microsoft. It was first released in 2015 as part of Windows 10 and Xbox One and later ported to other platforms as a fork of Google's Chromium open-source project: Android ...

, 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 applications, including

Firefox Mozilla Firefox, or simply Firefox, is a free and open-source web browser developed by the Mozilla Foundation and its subsidiary, the Mozilla Corporation. It uses the Gecko rendering engine to display web pages, which implements current ...

. The engine currently includes the IonMonkey compiler and OdinMonkey optimization module, has previously included the TraceMonkey compiler (first JavaScript JIT) and JägerMonkey. * JavaScriptCore: A JavaScript interpreter and JIT originally derived from KJS. It is used in the

WebKit 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 P ...

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 ...

engine used in ASP.NET based on Common Language Runtime and COM Interop. 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. *

Tamarin The tamarins are squirrel-sized New World monkeys from the family Callitrichidae in the genus ''Saguinus''. They are the first offshoot in the Callitrichidae tree, and therefore are the sister group of a clade formed by the lion tamarins, Goe ...

: 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 ...

and ECMAScript engine used in

Adobe Flash Adobe Flash (formerly Macromedia Flash and FutureSplash) is a multimedia software platform used for production of animations, rich web applications, desktop applications, mobile apps, mobile games, and embedded web browser video players. Fla ...

. * V8: A JavaScript engine used in Google Chrome and other Chromium-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 code o ...

, Deno, and V8.NET. *

GNU Guile GNU Ubiquitous Intelligent Language for Extensions (GNU Guile) is the preferred extension language system for the GNU Project and features an implementation of the programming language Scheme. Its first version was released in 1993. In addition ...

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 chassi ...

: A JavaScript engine used in Oracle

Java Development Kit The Java Development Kit (JDK) is a distribution of Java Technology by Oracle Corporation. It implements the Java Language Specification (JLS) and the Java Virtual Machine Specification (JVMS) and provides the Standard Edition (SE) of the Java ...

(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 Facebook is an online social media and social networking service owned by American company Meta Platforms. Founded in 2004 by Mark Zuckerberg with fellow Harvard College students and roommates Eduardo Saverin, Andrew McCollum, Dustin Mosk ...

for

React Native React Native is an open-source UI software framework created by Meta Platforms, Inc. It is used to develop applications for Android, Android TV, iOS, macOS, tvOS, Web, Windows and UWP by enabling developers to use the React framework along ...

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 In computer science, an interpreter is a computer program that directly execution (computers), executes instructions written in a Programming language, programming or scripting language, without requiring them previously to have been Compiler, co ...

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

web browser versions 9.50 to 10.10. * InScript: An obsolete

proprietary {{Short pages monitor