Using third party js libraries with Jint

Question

I'm working on a feature where user defined, anonymous, javascript functions retrieved from a database need to be executed server side in the context of ASP.Net application.

I'm evaluating Jint for this purpose (Latest version from NuGet). I have been able to run functions that do basic operations and return values without an issue as below.

    public void Do()
    {
        var jint = new Engine();
        var add = jint.Execute(@"var f = " + GetJsFunction()).GetValue("f");
        var value = add.Invoke(5, 4);
        Console.Write("Result: " + value);
    }

    private string GetJsFunction()
    {
        return "function (x,y) {" +
               "    return x+y;" +
               "}";
    }

My question is whether Jint facilitates the execution of javascript functions which uses third party libraries like lodash? If so, how would I go about making the Jint engine aware of it (i.e third party library)?

An example would be the execution of following function.

  private string GetFunction()
    {
        return "function (valueJson) { " +
               "   var value = JSON.parse(valueJson);" +
               "   var poi = _.find(value,{'Name' : 'Mike'});" +
               "   return poi; " +
               "}";

    }

Thanks a lot in advance.

score 1 · Accepted Answer · answered Jul 18 '16 at 09:14

I think I have figured this out. It's no different to executing a custom function. You just read the third party library from a file (project resource) and invoke execute on Jint engine. See below;

 private void ImportLibrary(Engine jint, string file)
    {
        const string prefix = "JintApp.Lib."; //Project location where libraries like lodash are located

        var assembly = Assembly.GetExecutingAssembly();
        var scriptPath = prefix + file; //file is the name of the library file
        using (var stream = assembly.GetManifestResourceStream(scriptPath))
        {
            if (stream != null)
            {
                using (var sr = new StreamReader(stream))
                {
                    var source = sr.ReadToEnd();
                    jint.Execute(source);
                }
            }
        }

    }

We can call this function for all the third party libraries that needs to be added.

Using third party js libraries with Jint

1 Answers1