Blazor .NET 10 New Features Print

Overview

Blazor in .NET 10 received significant improvements in performance, developer experience, and new capabilities. This article highlights the key features.

Performance Improvements

Blazor Script Optimization

The core blazor.web.js script is now served as a static asset with:

• 76% size reduction - from 183 KB to ~43 KB
• Automatic compression
• Fingerprinting for cache busting
• Faster load times

Hot Reload for WebAssembly

.NET 10 migrated to a general-purpose Hot Reload implementation:

• Edit .razor files and see changes instantly
• No rebuild required
• No browser refresh needed
• Works automatically - no configuration

New State Management

[PersistentState] Attribute

Declaratively persist component state during prerendering:

@code {
    [PersistentState]
    public string UserPreference { get; set; }
}

State is automatically persisted and retrieved when components render interactively.

Pause and Resume

New methods for Blazor Server state persistence:

• Blazor.pause() - Pause the circuit
• Blazor.resume() - Resume the circuit
• Users can resume where they left off after disconnection

Validation Enhancements

Source Generator Validation

.NET 10 replaces reflection-based validation with Source Generators:

• Faster validation at runtime
• AOT (Ahead-of-Time) compilation safe
• Better performance in WebAssembly

Nested Form Validation

New validation support for complex forms:

• AddValidation() method
• [ValidatableType] attribute (experimental)
• Validate nested objects and collections

Authentication - Passkeys Support

ASP.NET Core Identity now supports passkeys (WebAuthn/FIDO2):

• Passwordless authentication
• Biometric login (Windows Hello, Touch ID, Face ID)
• Security key support
• Phishing-resistant authentication

See our dedicated article on Blazor Authentication with Passkeys.

JavaScript Interop Improvements

• More efficient byte-array transfers in WASM
• Real JS object manipulation (similar to working directly with JavaScript)
• Better performance for JS-heavy applications

Developer Experience

Required Parameters

Required component parameters now trigger compile-time errors:

[Parameter, EditorRequired]
public string Title { get; set; }

Missing parameters are caught before runtime.

Build-Time Service Validation

WebAssembly builds now validate configured services at build time:

• Catch DI configuration errors early
• Fewer runtime surprises

Built-in ReconnectModal

Blazor Web App templates include a built-in reconnection UI:

• Developer-friendly reconnection modal
• Respects Content Security Policy (CSP)
• Customizable appearance

Navigation Improvements

• NavigateTo no longer forces scroll to top when navigating to same page
• Better handling of same-page navigation
• Improved anchor link behavior

Enhanced Debugging & Tracing

• OpenTelemetry integration for Blazor Server
• Performance profiling via .nettrace files for WebAssembly
• Better diagnostic capabilities

Migration Tips

1. Update target framework to net10.0
2. Update NuGet packages to .NET 10 versions
3. Review blazor.web.js references (now a static asset)
4. Test Hot Reload functionality
5. Consider implementing passkeys for authentication