Performance evolution 
In January 2009, the engine then known as SquirrelFish Extreme (SFX) was enabled for Mac OS X on x86-64 architectures as it passes all tests on that platform by Apple Inc. Released June 30, 2009, Firefox 3.5 includes the optimization technique that offered "performance improvements ranging between 20 and 40 times faster" compared to Firefox 3 in some cases.
- Rhino, managed by the Mozilla Foundation, open source, developed entirely in Java
- TraceMonkey, a tracing JIT compiler introduced with Firefox 3.5
- JägerMonkey, the engine introduced with Firefox 4
- IonMonkey, further JIT compiler optimizations for SpiderMonkey, introduced with Firefox 18
- Tamarin, by Adobe Labs
- V8 - open source, developed by Google in Denmark, part of Google Chrome
- Futhark, by Opera Software, replaced by Carakan in Opera 10.50 (released March 2010)
- Carakan, by Opera Software, used since Opera 10.50
- Narcissus open source, written by Brendan Eich, who also wrote SpiderMonkey
- Chakra, for Internet Explorer 9
- dyn.js, open source, written by Douglas Campos and others
- Nashorn, open source as part of OpenJDK, written by Oracle Java Languages and Tool Group
A dialect and an implementation are distinct: a dialect of a language is a significant variant of that language, while an implementation of a language (or dialect) executes a program written in that language (or dialect).
|Application||Dialect and latest version||ECMAScript edition|
and JScript extensions
|ECMA-262, edition 5.1|
See also 
- SunSpider – Browser speed test
- Shankland, Stephen (2008-09-02). "Speed test: Google Chrome beats Firefox, IE, Safari". CNET Business Tech. CBS Interactive. Retrieved 2010-06-28.
- "Big browser comparison test: Internet Explorer vs. Firefox, Opera, Safari and Chrome". PC Games Hardware. Computec Media AG. Retrieved 2010-06-28.
- "Lifehacker Speed Tests: Safari 4, Chrome 2". Lifehacker. Retrieved 2010-06-28.
- Shankland, Stephen (2008-09-02). "Third Chrome beta another notch faster". CNET. CBS Interactive. Retrieved 2010-06-28.
- Shankland, Stephen (2008-09-19). "Step aside, Chrome, for Squirrelfish Extreme". CNET. CBS Interactive. Retrieved 2010-06-29.
- Shankland, Stephen (2008-09-03). "Firefox counters Google's browser speed test". CNET Business Tech. CBS Interactive. Retrieved 2010-06-29.
- Garen, Geoffrey (2008-06-02). "Announcing SquirrelFish". Retrieved 2008-06-11.
- Lipskas, Vygantas (2008-06-11). "Apple Safari 4". Retrieved 2008-06-11.
- "Firefox 4 Vision: fast, powerful, and empowering".
- http://www.prnewswire.com/news-releases/apple-releases-safari-5-95817479.html Safari 5 Released
- "Firefox 18 Release Notes introducing IonMonkey".
- Marius Oiaga (2010-03-20), "Internet Explorer 9 Beta Next – New IE9 Builds Every 8 Weeks", softpedia.com (SoftNews NET SRL), retrieved 2010-06-28
- J. Laskey (2011-07-19), Adventures in JSR-292 or How To Be A Duck Without Really Trying, Oracle
- "Web specifications support in Opera Presto". Opera.com. Opera Software ASA. Retrieved 2010-06-28.
- Peacekeeper – Browser speed test