The roslyn compiler found in Visual Studio 14 enables us, to adjust C# code during runtime, by compiling the new C# code in-memory. Now we can edit the UI part (HTML, CSS, JavaScript) of a single page app, including the backend C# ASP .NET Web Api service dynamically in runtime.


On of the things, that disrupts my workflow, when creating a single page app with AngularJS, backed by a web api C# service in Visual Studio 2013, is the fact that, when I find a bug in my C# code while testing the UI, I have to stop the debugger, adjust the web api C# code, re-compile, re-run and then recreating state in the web app before I can resume testing the UI.

This pain will go away, when using Visual Studio 14


Download and install Visual Studio 14 CTP 3 from

Open Visual Studio, choose File > New > Project …






Start the web application by pressing CTRL + F5 (so don’t start the debugger).




Click on the Contact page in the browser:

You will see the text “Your contact page”.



Now go to the Controllers\HomeController.cs



Adjust the the C# code: ViewBag.Message = "Your contact page.";


ViewBag.Message = "My contact page.";




Save the file and in the browser press F5, you might see a short delay, because the roslyn compiler is now dynamically compiling the code.


The C# code is changed without disrupting my workflow.




  1. What ever happened to this. Now that we are with .Net Core, this workflow would be highly desirable… but seems to still be lacking in VS 2017

  2. But in your screenshots you are changing the code when app is not in running mode .That is possible and even we can use the pause icon on the top to edit the code .The solution i want is that i can change the code while in run mode .Something like Nodemon for node.js.


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