blazor-expert

Blazor components are reusable UI units with lifecycle methods (@OnInitializedAsync, OnParametersSet), parameter binding via [Parameter], and EventCallback for parent-child communication. Organize components hierarchically, pass data down as parameters, and communicate state changes back through callbacks to maintain unidirectional data flow.

Blazor supports authentication workflows using AuthenticationStateProvider to access current user claims and CascadingAuthenticationState to pass auth context to components. Implement authorization checks with [Authorize] attributes, role-based access control, and policy-based authorization to protect routes and component content.

JavaScript interop in Blazor uses IJSRuntime to invoke JS functions from C# code. For scalability and isolation, organize JS in ES modules and import them dynamically to avoid global namespace pollution. Handle async operations with Task-returning methods and proper error handling for robust interop.

EditForm component with DataAnnotations validation attributes ([Required], [StringLength], etc.) provides client-side validation feedback. Bind form fields to a model object, handle OnValidSubmit callback for validated submissions, and display validation messages using ValidationMessage components tied to model properties.

Blazor routing uses @page directives to map URL patterns to components, supporting route parameters and constraints. Both Server and WebAssembly use the same routing syntax, but Server handles navigation server-side while WebAssembly performs client-side routing without page reloads, affecting performance and state persistence differently.

Optimize Blazor by implementing virtualization for large lists, controlling re-renders with ShouldRender override, lazy-loading components, minimizing interop calls, and applying code splitting in WebAssembly builds. Server apps benefit from circuit optimization; WebAssembly apps gain from ahead-of-time compilation and reduced initial download size.