List of languages that compile to JS

CoffeeScript Family (& Friends)

• CoffeeScript Unfancy JavaScript

Family (share genes with CoffeeScript)

• Coco A CoffeeScript dialect that aims to be more radical and practical, also acts as a test bed for features that get imported in CoffeeScript.
• Parsec CoffeeScript CS based on parser combinators. The project's aim is to add static metaprogramming (i.e. macros + syntax extensibility) to Coffee Script (CS), similar to how Metalua adds such features to Lua. The resulting compiler, once merged with the official compiler, should be usable as a drop-in replacement for it.

Friends (philosophically related)

• JS11 Beautiful like CoffeeScript but far more conventional, in case you have no interest in Ruby-like syntax. Also debugs line-for-line as JS.
• Kaffeine Enhanced Syntax for JavaScript.
• Jack Making programming playful.
• move A simpler and cleaner programming language.

JavaScript

• Narcissus Mozilla's experimental JavaScript compiler in JavaScript by Brendan Eich and others.
  • CommonJS version in DoctorJS
  • Jasy: Python port of Narcissus with some enhancements
• Traceur Google's vehicle for Javascript Language Design Experimentation
• Closure Compiler An optimizing compiler. Can generate a (line/col)-number mappings file.
• UglifyJS
• bdParse a JavaScript LL(1) parser in JavaScript

Security enforcing JavaScript

• Caja Compiles ES5/strict to ES3 and supports object-capabilities
• ADsafe Client-side static verifier and API, making third party scripts safe.
• FBJS Facebook JavaScript, used for scripting FBML (Facebook Markup Language) gadgets.
• Jacaranda Static verifier supporting object-capabilities.
• Microsoft Web Sandbox Technology preview of securing web content through isolation.
• Gatekeeper Microsoft Research project.
• Dojo Secure Framework for building secure mashups.

Synchronous to Asynchronous JavaScript Compilers (CPS)

• Streamline.js Uses underscore (_) to stand for callbacks. This fork preserves line numbers for debugging.
• mobl The new language for programming the mobile web.
• StratifiedJS JavaScript + structured concurrency. See also apollo on that site.
• NarrativeJS JavaScript extension with asynchronous futures and promises.
• jwacs JavaScript With Advanced Continuation Support.
• Jscex Write simple JavaScript code, execute it asynchronously by compiling to monadic form. Works in any ECMAScript 3 engines directly.

JavaScript Language Extensions

• ContextJS is an implementation of Context-oriented Programming for JavaScript.
• Objective-J Shares with JavaScript the same relationship that Objective-C has with the C programming language: that of being a strict, but small, superset.
• JS2 Object-oriented JavaScript with syntactic sugar (curry, foreach, property). Released as a Ruby gem.
• jangaroo AS3 (ActionScript) to JavaScript.
• Flapjax Event-driven, reactive evaluation.
• jLang adds object oriented syntax, namespaces, operators overriding

Ruby

• HotRuby Runs opcode, compiled by YARV on Ruby inside a web browser or in Flash.
• rb2js Converts Ruby to JavaScript.
• Red Writes like Ruby and runs like JavaScript
• Quby Used for game coding site, not open source.
• Opal Ruby to Javascript compiler.

Python

• PYXC-PJ [CS friend] Python to JS. Can generate a (line/col)-number mappings file.
• Pyjamas Python to JS.
• Skulpt Python. Client side.
• PyCow Python to MooTools JS.
• PyvaScript Python-like syntax to JavaScript.

Java

• GWT Google Web Toolkit, compiles java to javascript
• Java2Script Eclipse Java to JavaScript compiler plugin and JavaScript version of SWT
• j2js Java bytecode to JavaScript.

Lisp, Scheme

• clojurejs Subset of Clojure to JS.
• ClojureScript Translates code written in a very small subset of Clojure.
• EdgeLisp A Lisp in the tradition of Common Lisp
• Fargo Scheme in JavaScript
• Moby Scheme A Scheme running in JS.
• Parenscript Subset of Common Lisp to JS.
• Ralph Lisp-1 dialect that compiles to JavaScript, inspired by Dylan
• scheme2js Scheme to JavaScript.
• Scriptjure Library for generating JavaScript from Clojure forms.
• Sibilant JavaScript with a lisp.
• Spock A Scheme to JavaScript compiler that uses Henry Baker's Cheney-on-the-MTA compilation strategy

OCaml

• Ocamljs OCaml to JS.
• O'Browser OCaml bytecode interpreter in JS.
• Js_of_ocaml OCaml bytecode to JS compiler.

Haskell

• UHC (Utrecht Haskell Compiler) backend converts UHC core to JavaScript, allowing the compiling of Haskell code to JS.
• YHC (York Haskell Compiler) backend, as above but with YHC core language.

Smalltalk

• Clamato a Smalltalk dialect that is designed to operate within the JavaScript runtime.
• Silver Smalltalk [commercial] Smalltalk in the browser.
• JTalk An implementation of the Smalltalk language that runs on top of the JavaScript runtime.
• Lively Kernel - smalltalk/squeak-like development environment in the browser

C/C++

• Emscripten LLVM to JavaScript compiler.
• mala vala (gobject) to javascript
• Clue C language compiler to different runtimes (Lua, JS, Perl 5, C, Java, CL).

Basic

• NS Basic/App Studio [commercial] Visual Basic-style BASIC to JavaScript compiler. Includes IDE. Targets iOS and Android.
• qb.js An implementation of QBASIC in Javascript

Multitarget

• Haxe compiles to several platforms (C++, Flash, JS, Neko, PHP).
• Fantom Evolutionary object-oriented language emphasizing succinct and effective APIs (JVM, CLR, JS).
• Clue C language compiler to different runtimes (Lua, JS, Perl 5, C, Java, CL).
• jsc [experimental] Recompile your .NET assembly to JavaScript, ActionScript, PHP or Java.

Tierless languages (produce both client & server)

• One Pot Application [free for non commercial] Industrial programming language for high-security distributed web applications.
• Fun A programming language for realtime webapps - compiles to client-side and server-side JS.
• Ur In the tradition of ML and Haskell.
• WebSharper Lets you compile F# to JS.
• mobl The new language for programming the mobile web.
• E Compiles E to JS. E is a secure distributed persistent pure object language.
• Sugar new programming language designed to replace JavaScript for client-side (and server-side) web development

Others

• Oia A port of Io to JavaScript.
• newspeak in progress, converting compiler from java to javascript
• Quixe a Glulx VM interpreter written in Javascript
• Gnusto a Z-Machine VM interpreter written in Javascript
• Logo Interpreter
• TIScript

Static typed

• Some of the ones listed above are statically typed, such as mobl, GWT, NS Basic, and Haxe.
• Script# [commercial] Compiles C# to JS.
• MileScript [commercial] A strongly-typed language similar to C# and Java, but which compiles to JS. free for non-profit, educational use.
• Mascara [commercial] Enhances JavaScript with powerful features like classes, namespaces and type-checking.

Tools for Compiler Writers

Javascript Parser Generators

• jison Bison in javascript, used by Coffeescript
• OMeta/JS (source) metacompiler for many languages to many targets, including js.
• PEG.js parser generator for JavaScript based on the parsing expression grammar formalism
• Canopy Self-hosting PEG parser compiler for JavaScript, influenced by Ruby parser generators such as Treetop and Citrus. Depends on JS.Class library
• JS/CC LALR(1) parser generator
• jsparse
• ReParse parser combinator library for Javascript like Haskell's Parsec
• p4js Monadic parser library for JavaScript
• JSGLR Scannerless, Generalized Left-to-right Rightmost (SGLR) derivation parser for JavaScript
• antlr has a javascript target
• Cruiser.Parse LL(k) parser

Javascript AST

• Closure Compiler AST Documentation
• JsonML AST format used by the es5 parser
• treehugger Javascript AST transformation tools