The following test case raise an exception:

    [TestMethod]
    public void Test2()
    {
        Expression<Func<MyClass, string>> expr = x => x.Name.ToLower();
        var js = expr.CompileToJavascript(new JavascriptCompilationOptions(JsCompilationFlags.ScopeParameter));          
        Assert.AreEqual("function(Name){return Name.toLowerCase();}", js);     
    }

Exception error:

      Test method Lambda2Js.Tests.GeneralTests.Test1 threw exception: 
       System.NotSupportedException: By default, Lambda2Js cannot convert custom instance methods, only static ones. `ToLower` is not static.

...

Can lambda2js support the built-in functions that have a corresponding one in js?
e.g the string method ToLower() ===> can be mapped to js toLowerCase()

I need a tool that will take a C# LINQ Expression tree, like the input for this project, but rather than create JavaScript out of it, it evaluates it on demand -- it would be somewhat equivalent to creating JavaScript and then using a JavaScript interpreter on it. But what I want is given the expression tree, I want to actually evaluate it by interpreting on demand.

I realize I can call .Compile() on the expression and run it, but I can't do that for my project.

I'm thinking of starting with this project as an example and then removing the JavaScript generation code and replacing it with an interpreter. If I did that, are there any issues or limitations that you guys think I might run into?

Hi,

Are you planning to .NET Core support?

I'm using Lambda2Js.Signed as a transitive dependency of RavenDb.Client in a .NET Framework 4.7.2 application.

Lambda2Js.Signed's NuGet package has a net40 lib and a netstandard1.0 lib. Since I'm using .NET Framework, NuGet package manager picks the latest .NET Framework version of the package, net40. This would be fine, except the net40 package has some compatbility definitions of types that exist in mscorlib in .NET 4.5 and later, such as System.Threading.Interlocked. Because of this, my application is full of warnings like warning CS1685: The predefined type 'System.Threading.Interlocked' is defined in multiple assemblies in the global alias; using definition from 'c:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.2\mscorlib.dll'

I am able to manually edit my csproj to use the netstandard1.0 lib instead of net40, which resolves the issue. But any updates through NuGet package manager will reverse this, making this dependency fragile.

Would it be possible to add a new net45 lib to the NuGet package that doesn't contain the net40 compatibility types? This would help anyone on .NET Framework 4.5 or later.

If you make the nuget package part of this repository then I could add a .NET 4.0 target so that I could use it in my solution via nuget.

Provide a way to globally define extensions to use in the compilation process. At this moment, the only way to tell what extensions to use it through the CompileToJavascript method.

Create a NuGet package and submit it to nuget.org

Hi, I am using the JetBrains.Annotations NuGet package and have experienced a compatibility issue with your Lambda2js NuGet package (which the jetbrains package uses as a dependency).

I reported the problem here: JetBrains/JetBrains.Annotations#4

Hi, I hope this is the right place to report a bug. I cannot use [UsedImplicitly(ImplicitUseTargetFlags.WithInheritors)] in my codebase because there is a dependency issue with JetBrains.Annotations. It says:

The type 'ImplicitUseTargetFlags' exists in both 'JetBrains.Annotations, Version=2021.2.0.0, ...' and 'Lambda2Js.Signed, Version=3.1.3.0, ...',

but JetBrains.Annotations has a dependency on .NetStandard v1.0, and .NetStandard v1.0 has a dependency on that Lambda2Js.Signed package, so I cannot fix the dependency problem myself.

I want to use these flags (e.g., ImplicitUseTargetFlags) but can only use the UsedImplicitly attribute without flags. I hope this can get fixed as inheritance would be a great feature to use with these attributes. This would let me have a base class with the UsedImplicitly attribute and then all my derived classes would not need to also have this attribute and it can be assumed that if I'm deriving from the base class then it will be used implicitly (which is great for many design patterns). Thank you.

But they closed it and said I might want to open up an issue with your library instead.

When serializing initialization like this:

public class MyClass
{
    [JsonProperty(PropertyName = "custom_name")]
    public string Name { get; set; }
}

public delegate object MyFuncDef(string name);

Expression<MyFuncDef> expr = name => new MyClass { Name = name };

var js = expr.CompileToJavascript(
        new JavascriptCompilationOptions(
            (JsCompilationFlags)0,
            MemberInitAsJson.ForAllTypes));

It does not work. Result is:

function(name){return {Name:name};}

But should be:

function(name){return {custom_name:name};}

usage of conditional ?: operator like:

Expression<Func<Tuple<bool,int>,int>> expr = row => row.Item1?2*row.Item2:1;
Console.WriteLine(expr.CompileToJavascript(new JavascriptCompilationOptions(JsCompilationFlags.BodyOnly)));

results in blank output:

Press any key to continue . . .

where one would expect:
row.Item1?2*row.Item2:1
Press any key to continue . . .

Hi, are there any plans for releasing version 3.1.1 with latest fixes?

This new test throws a null pointer exception.

[TestMethod] public void NullLiteralToString() { Expression<Func<string>> expr = () => null; var js = expr.Body.CompileToJavascript(); Assert.AreEqual("null", js); }

The current nuget package doesn't work with .NET 4.0 project and it seems it is because the lib has a folder for: portable-net403%2Bsl50%2Bwin%2Bwpa81%2Bwp80.

When I change it to: portable-net40%2Bsl50%2Bwin%2Bwpa81%2Bwp80 (I removed the 3 in net403)

Then it works.

Place some samples in the readme

Hey @masbicudo, thanks for this great library!

I was wondering if there is a way to convert this...

x => x.SomeEnumProperty == MyEnum.HelloWorld

to this...

SomeEnumProperty === 'HelloWorld'

instead of this...

SomeEnumProperty === 0

In C# most property names follow the PascalCaseConvention. In JavaScript it's more common to use camelCaseConvention.

There should be an option to allow the conversion.

I have the expression:

Expressions.Expression<Func<string, bool>> asd = x => x == "qwe";
Console.WriteLine(asd.CompileToJavascript());

This throws an NotSupportedException:
"The used constant value is not supported: False (Boolean)"

Kris

Is there a possibility for the DLLs to be signed? I'm getting following error:

CS8002: Referenced assembly 'Lambda2Js, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' does not have a strong name.

Using '3.0.1' NuGet package. The '1.0.0.0' also means that the File version is not set.