blazor-lumen-boilerplate

Blazor at a glance

Blazor is a framework for building interactive client-side web UI with .NET.

Components

Blazor apps are based on components. A component in Blazor is an element of UI, such as a page, dialog, or data entry form.

Components are .NET C# classes built into .NET assemblies that:

• Define flexible UI rendering logic.
• Handle user events.
• Can be nested and reused.
• Can be shared and distributed as Razor class libraries or NuGet packages.

The component class is usually written in the form of a Razor markup page with a .razor file extension. Components in Blazor are formally referred to as Razor components. Razor is a syntax for combining HTML markup with C# code designed for developer productivity. Razor allows you to switch between HTML markup and C# in the same file.

Blazor WebAssembly

Blazor WebAssembly is a single-page app (SPA) framework for building interactive client-side web apps with .NET. Blazor WebAssembly uses open web standards without plugins or recompiling code into other languages. Blazor WebAssembly works in all modern web browsers, including mobile browsers.

Running .NET code inside web browsers is made possible by WebAssembly (abbreviated wasm). WebAssembly is a compact bytecode format optimized for fast download and maximum execution speed. WebAssembly is an open web standard and supported in web browsers without plugins.

WebAssembly code can access the full functionality of the browser via JavaScript, called JavaScript interoperability, often shortened to JavaScript interop or JS interop. .NET code executed via WebAssembly in the browser runs in the browser’s JavaScript sandbox with the protections that the sandbox provides against malicious actions on the client machine.

When a Blazor WebAssembly app is built and run in a browser:

• C# code files and Razor files are compiled into .NET assemblies.
• The assemblies and the .NET runtime are downloaded to the browser.
• Blazor WebAssembly bootstraps the .NET runtime and configures the runtime to load the assemblies for the app. The Blazor WebAssembly runtime uses JavaScript interop to handle DOM manipulation and browser API calls.

The size of the published app, its payload size, is a critical performance factor for an app’s usability. A large app takes a relatively long time to download to a browser, which diminishes the user experience. Blazor WebAssembly optimizes payload size to reduce download times:

• Unused code is stripped out of the app when it’s published by the Intermediate Language (IL) Trimmer.
• HTTP responses are compressed.
• The .NET runtime and assemblies are cached in the browser.

JavaScript interop

For apps that require third-party JavaScript libraries and access to browser APIs, components interoperate with JavaScript. Components are capable of using any library or API that JavaScript is able to use. C# code can call into JavaScript code, and JavaScript code can call into C# code.

Additional resources

• WebAssembly
• C# Guide
• [HTML] (https://www.w3.org/html/)

This site is open source. Improve this page.