TypeScript lambda expression
In my opinion, TypeScript is the best solution for MS/.NET oriented development.
At first - it is very similar to C#, that makes .NET developer's life easy.
At third (but not less important) - it has Lambda expression
I am using JQuery AJAX, and used to write such code:
It is simple closure, that I use to keep reference to the instance that I work with from ajax callback.
This pattern became routine and very annoying.
But TypeScript bring the solution:
It worth to move to TypeScript just because it is a great feature