msgpack5 | msgpack v5 implementation for node.js , with extension points

When serializing and deserializing values between JavaScript and C# using SignalR with MessagePack I am seeing a bit of precision loss in C# on the receiving end.

As an example I am sending the value 0.005 from JavaScript to C#. When the deserialized value appears on the C# side I am getting the value 0.004999999888241291, which is close, but not 0.005 exactly. The value on the JavaScript side is Number and on the C# side I am using double.

I have read that JavaScript can't represent floating point numbers exactly which can lead to results like 0.1 + 0.2 == 0.30000000000000004. I suspect the issue I am seeing is related to this feature of JavaScript.

The interesting part is that I am not seeing the same issue going the other way. Sending 0.005 from C# to JavaScript results in the value 0.005 in JavaScript.

Edit: The value from C# is just shortened in the JS debugger window. As @Pete mentioned it does expand to something that is not 0.5 exactly (0.005000000000000000104083408558). This means the discrepancy happens on both sides at least.

JSON serialization does not have the same issue since I am assuming it goes via string which leaves the receiving environment in control wrt parsing the value into its native numerical type.

I am wondering if there is a way using binary serialization to have matching values on both sides.

If not, does this mean that there is no way to have 100% accurate binary conversions between JavaScript and C#?

Technology used:

• JavaScript
• .Net Core with SignalR and msgpack5

My code is based on this post. The only difference is that I am using ContractlessStandardResolver.Instance.