Skip to content
Go to file


Build status

What is Jurassic?

Jurassic is an implementation of the ECMAScript language and runtime. It aims to provide the best performing and most standards-compliant implementation of JavaScript for .NET. Jurassic is not intended for end-users; instead it is intended to be integrated into .NET programs. If you are the author of a .NET program, you can use Jurassic to compile and execute JavaScript code.


  • Supports all ECMAScript 3 and ECMAScript 5 functionality, including ES5 strict mode
  • Well tested - passes over five thousand unit tests (with over thirty thousand asserts)
  • Simple yet powerful API
  • Compiles JavaScript into .NET bytecode (CIL); not an interpreter
  • Deployed as a single .NET assembly (no native code)
  • Basic support for integrated debugging within Visual Studio
  • Uses light-weight code generation, so generated code is fully garbage collected
  • Tested on .NET 3.5, .NET 4 and Silverlight

How do I get it?

Install the NuGet package.


See the wiki for full usage details.

ECMAScript 6 status

Support for ECMAScript 6 is in progress. See for the definition of each feature. The table below is correct as of version 3.1.

Feature Status
  proper tail calls (tail call optimisation)
  default function parameters 4/7
  rest parameters
  spread syntax for iterable objects
  object literal extensions 6/6
  for..of loops 6/9
  octal and binary literals 4/4
  template literals 6/7
  RegExp "y" and "u" flags
  destructuring, declarations
  destructuring, assignment
  destructuring, parameters
  Unicode code point escapes 4/4 2/2
  const 18/18
  let 14/16
  block-level function declaration[18]
  arrow functions
  class 24/24
  super 8/8
  typed arrays 45/46
  Map 18/19
  Set 18/19
  WeakMap 11/12
  WeakSet 10/11
  Proxy [25]
  Reflect [26]
  Promise 4/8
  Symbol 8/12
  well-known symbols[27] 7/26
Built-in extensions
  Object static methods 4/4
  function "name" property 10/17
  String static methods 2/2
  String.prototype methods 10/10
  RegExp.prototype properties 2/6
  Array static methods 8/11
  Array.prototype methods 9/10
  Number properties 9/9
  Math methods 17/17
  Date.prototype[Symbol.toPrimitive] 1/1
  Array is subclassable 3/11
  RegExp is subclassable 3/4
  Function is subclassable 4/6
  Promise is subclassable
  miscellaneous subclassables
  prototype of bound functions 1/5
  Proxy, internal 'get' calls
  Proxy, internal 'set' calls
  Proxy, internal 'defineProperty' calls
  Proxy, internal 'deleteProperty' calls
  Proxy, internal 'getOwnPropertyDescriptor' calls
  Proxy, internal 'ownKeys' calls
  Object static methods accept primitives 10/10
  own property order 2/7
  Updated identifier syntax 1/3
  miscellaneous 7/9
Annex b
  non-strict function semantics[35] 2/3
  __proto__ in object literals [36]
  Object.prototype.__proto__ 1/6
  String.prototype HTML methods 3/3
  RegExp.prototype.compile 1/2
  RegExp syntax extensions 4/8
  HTML-style comments
You can’t perform that action at this time.