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ClearScript is a library that makes it easy to add scripting to your .NET applications. It currently supports JavaScript (via V8 and JScript) and VBScript.


  • Simple usage; create a script engine, add your objects and/or types, run scripts
  • Support for several script engines: Google's V8, Microsoft's JScript and VBScript
  • Exposed resources require no modification, decoration, or special coding of any kind
  • Scripts get simple access to most of the features of exposed objects and types:
    • Methods, properties, fields, events
    • (Objects) Indexers, extension methods, conversion operators, explicitly implemented interfaces
    • (Types) Constructors, nested types
  • Full support for generic types and methods, including C#-like type inference and explicit type arguments
  • Scripts can invoke methods with output parameters, optional parameters, and parameter arrays
  • Script delegates enable callbacks into script code
  • Support for exposing all the types defined in one or more assemblies in one step
  • Optional support for importing types and assemblies from script code
  • The host can invoke script functions and access script objects directly
  • Full support for script debugging


using System;
using Microsoft.ClearScript;
using Microsoft.ClearScript.JavaScript;
using Microsoft.ClearScript.V8;

// create a script engine
using (var engine = new V8ScriptEngine())
    // expose a host type
    engine.AddHostType("Console", typeof(Console));
    engine.Execute("Console.WriteLine('{0} is an interesting number.', Math.PI)");

    // expose a host object
    engine.AddHostObject("random", new Random());

    // expose entire assemblies
    engine.AddHostObject("lib", new HostTypeCollection("mscorlib", "System.Core"));

    // create a host object from script
        birthday = new lib.System.DateTime(2007, 5, 22);

    // use a generic class from script
        Dictionary = lib.System.Collections.Generic.Dictionary;
        dict = new Dictionary(lib.System.String, lib.System.Int32);
        dict.Add('foo', 123);

    // call a host method with an output parameter
    engine.AddHostObject("host", new HostFunctions());
        intVar = host.newVar(lib.System.Int32);
        found = dict.TryGetValue('foo', intVar.out);
        Console.WriteLine('{0} {1}', found, intVar);

    // create and populate a host array
        numbers = host.newArr(lib.System.Int32, 20);
        for (var i = 0; i < numbers.Length; i++) { numbers[i] = i; }
        Console.WriteLine(lib.System.String.Join(', ', numbers));

    // create a script delegate
        Filter = lib.System.Func(lib.System.Int32, lib.System.Boolean);
        oddFilter = new Filter(function(value) {
            return (value & 1) ? true : false;

    // use LINQ from script
        oddNumbers = numbers.Where(oddFilter);
        Console.WriteLine(lib.System.String.Join(', ', oddNumbers));

    // use a dynamic host object
        expando = new lib.System.Dynamic.ExpandoObject(); = 123; = 'qux';

    // call a script function
    engine.Execute("function print(x) { Console.WriteLine(x); }");

    // examine a script object
    engine.Execute("person = { name: 'Fred', age: 5 }");

    // read a JavaScript typed array
    engine.Execute("values = new Int32Array([1, 2, 3, 4, 5])");
    var values = (ITypedArray<int>)engine.Script.values;
    Console.WriteLine(string.Join(", ", values.ToArray()));

Last edited Sep 14 at 1:49 AM by ClearScript, version 70