The default template’s supplied for Blazor Server and WebAssembly applications, gives you lots upfront. However, ofcourse you’re likely to want to import further functionality via the @using directive.

For example, let’s say we want to add the following to the Counter.razor IncrementCount method (from the default template generated files)

Debug.WriteLine("Increment");

We can simply add the following to the top of the Counter.razor file

@using System.Diagnostics

Alternatively and especially useful for using code across multiple pages/components, you can put the above code into the _Imports.razor file. Think of this as a global set of using reference, but only for @code sections, for standard C# classes we ofcourse use the using directive as usual.

Note: I’ve found my current version of Visual Studio doesn’t seem to immediately recognise the updated _Imports.razor file, a build fixes that.