Start writing a Blazor app in seconds

As of today, if you want to start writing a Blazor app in just few seconds, you can follow the official get started guide which requires mainly 3 points:

  • Install the latest .NET Core 3.0 SDK release
  • Install the latest Blazor template by running dotnet new -i Microsoft.AspNetCore.Blazor.Templates::3.0.0-*
  • Create a new Blazor WebAssembly project by running:
    • dotnet new blazorwasm -o MyBlazorWebAssemblyProject,
    • then cd MyBlazorWebAssemblyProject
    • and finally dotnet run

That’s all, you get a running Blazor WebAssembly web app that you can start developping/debugging.

If you want to publish it, just run dotnet publish -c release and copy the content of the publish/dist folder to your favourite static files hosting platform, and you are done!

And if like me, you don’t like when too much magic is done for you, keep reading the following sections :)

Smallest publishable static Blazor project

To create the smallest client side Blazor app possible, we will need first a .csproj file at it is a C# project. Inside we will be able to reference the Blazor specific tooling, as well as mandatory dependencies (3 exactly: Microsoft.AspNetCore.Blazor, Microsoft.AspNetCore.Blazor.Build and Microsoft.AspNetCore.Blazor.HttpClient)

Then like any classic ASP.NET core project, you will need a Program.cs file which will be calling the Startup.cs file. The latest will be in charge of referencing you root Blazor component.

Then for the real Blazor stuff, you will need your root Blazor component file, usually named App.razor by convention, and also your default page usually called Index.razor, placed inside a Pages folder.

To glue all of that stuff, you will also need to create an index.html file inside the wwwroot folder. In this file, you will find a reference to the blazor.webassembly.js framework which will be in charge of loading the mono webassembly runtime, as well as your project assemblies which need to be defined inside a blazor.boot.json file (You can have a look at the schema described in What is Blazor).

You can find below a small recap list of the mentionned files:

  • A C# project .csproj file,
  • A entry Program.cs file,
  • A Startup.cs file following the startup pattern,
  • An App.razor root Blazor component,
  • An Index.razor page inside of a Pages folder (by convention),
  • And finally an index.html file inside of the wwwroot folder, which will be the starting point.

You can have a look at the content of all these files on my Github commit #ADD smallest publishable static Blazor project, but at this level, they are pretty much empty.

Now you should have a deployable project, for which you can run dotnet publish -c release and browse into the folder ./bin/release/netstandard2.0/publish/MyBlazorWebAssemblyProject/dist to find all the static files you need to run your Blazor app (We will see in future articles how to host)

01-blazor-smallest-publishable-project

We still get to download 5.1MB to display our Blazor app, mainly due to the size of the mono.wasm and the mscorlib.dll files which weight 1.8MB and 1.3MB respectively.

But like most SPA app, since these files are static files, they should ideally be downloaded only once, keeping the reload of the web page to only a few KB fortunately :)

In conclusion

Well, I hope this article helped you to get a better understanding of what is really needed to get a simple Blazor app without any magic!

In the next article, I plan on writing about hosting this small Blazor app (in a Docker container for instance :))

Feel free to reach me out on Twitter @vivienfabing or anywhere else, and may the code be with you!