A Comprehensive Guide to Building Web Applications with Blazor

Blazor is a powerful framework from Microsoft that allows you to build interactive web applications using C# and .NET. It leverages WebAssembly to run .NET code directly in the browser, offering a rich development experience similar to frameworks like Angular or React. This guide will take you through the process of building a Blazor application, step by step, with examples of API consumption and component interactions.

Table of Contents

1. Introduction to Blazor
2. Setting Up Your Blazor Project
3. Creating Components in Blazor
4. Data Binding and Event Handling
5. Consuming APIs in Blazor
6. Component Interactions
7. Differences with ReactJS and NextJS
8. Deploying Your Blazor Application
9. Conclusion

1. Introduction to Blazor

Blazor comes in two flavors:

• Blazor WebAssembly (WASM): Runs in the browser via WebAssembly.
• Blazor Server: Runs on the server and uses SignalR to update the client.

In this guide, we’ll focus on Blazor WebAssembly, but many concepts apply to Blazor Server as well.

2. Setting Up Your Blazor Project

First, ensure you have the .NET SDK installed. You can download it from Microsoft’s official site.

Create a new Blazor WebAssembly project using the following command:

dotnet new blazorwasm -o BlazorApp
cd BlazorApp

Next, open the project in your preferred IDE (Visual Studio, Visual Studio Code, etc.).

3. Creating Components in Blazor

Components are the building blocks of a Blazor application. They are .razor files and can include HTML, C#, and Razor syntax.

Create a new component named Counter.razor:

@page "/counter"
@code {
    private int currentCount = 0;

    private void IncrementCount()
    {
        currentCount++;
    }
}

<h3>Counter</h3>

<p>Current count: @currentCount</p>

<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>

This simple component includes a button that increments a counter.

4. Data Binding and Event Handling

Blazor supports both one-way and two-way data binding. Here’s an example of a component with two-way data binding:

Create a new component named DataBindingExample.razor:

@page "/databinding"
@code {
    private string name = "";

    private void HandleSubmit()
    {
        Console.WriteLine($"Hello, {name}!");
    }
}

<h3>Data Binding Example</h3>

<input @bind="name" placeholder="Enter your name" />
<button class="btn btn-primary" @onclick="HandleSubmit">Submit</button>

<p>You entered: @name</p>

5. Consuming APIs in Blazor

Blazor can consume APIs using HttpClient. First, configure HttpClient in Program.cs:

builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });

Next, create a service to fetch data. Create a new folder Services and add a file WeatherService.cs:

using System.Net.Http;
using System.Net.Http.Json;
using System.Threading.Tasks;

public class WeatherService
{
    private readonly HttpClient _httpClient;

    public WeatherService(HttpClient httpClient)
    {
        _httpClient = httpClient;
    }

    public async Task<WeatherForecast[]> GetWeatherForecasts()
    {
        return await _httpClient.GetFromJsonAsync<WeatherForecast[]>("sample-data/weather.json");
    }
}

Register the service in Program.cs:

builder.Services.AddScoped<WeatherService>();

Create a WeatherForecast.razor component to display the data:

@page "/weather"
@inject WeatherService WeatherService

@code {
    private WeatherForecast[] forecasts;

    protected override async Task OnInitializedAsync()
    {
        forecasts = await WeatherService.GetWeatherForecasts();
    }
}

<h3>Weather forecast</h3>

@if (forecasts == null)
{
    <p><em>Loading...</em></p>
}
else
{
    <table class="table">
        <thead>
            <tr>
                <th>Date</th>
                <th>Temperature (C)</th>
                <th>Summary</th>
            </tr>
        </thead>
        <tbody>
            @foreach (var forecast in forecasts)
            {
                <tr>
                    <td>@forecast.Date.ToShortDateString()</td>
                    <td>@forecast.TemperatureC</td>
                    <td>@forecast.Summary</td>
                </tr>
            }
        </tbody>
    </table>
}

6. Component Interactions

Components can interact with each other using parameters and cascading values.

Create a parent component ParentComponent.razor:

@page "/parent"
@code {
    private string parentMessage = "Message from Parent";
}

<h3>Parent Component</h3>

<p>Parent's message: @parentMessage</p>

<ChildComponent MessageFromParent="@parentMessage" />

Create a child component ChildComponent.razor:

@code {
    [Parameter]
    public string MessageFromParent { get; set; }
}

<h3>Child Component</h3>

<p>Received message: @MessageFromParent</p>

7. Differences with ReactJS and NextJS

Blazor, ReactJS, and NextJS are all popular frameworks for building modern web applications, but they have distinct differences. This section delves deeper into their core aspects to help you understand which one might be the best fit for your needs.

Language and Ecosystem

Blazor

• Language: Blazor uses C# for both client-side and server-side logic. This is beneficial for developers who are already familiar with the .NET ecosystem.
• Ecosystem: It integrates seamlessly with the .NET ecosystem, including libraries and tools like Entity Framework, ASP.NET Core, and Azure services. The .NET ecosystem is mature and provides robust support for enterprise-level applications.
• Advantages: Uniform language for both front-end and back-end, strong typing with C#, rich tooling support in Visual Studio.

ReactJS

• Language: React uses JavaScript, the most popular language for web development. TypeScript, a superset of JavaScript, is also commonly used to provide static typing.
• Ecosystem: React has a vast ecosystem with countless libraries for state management (Redux, MobX), routing (React Router), and UI components (Material-UI, Ant Design). The React community is very active, providing extensive resources and third-party libraries.
• Advantages: Extensive library support, large community, flexibility in choosing tools and libraries, high performance due to the virtual DOM.

NextJS

• Language: Next.js, built on React, also uses JavaScript or TypeScript.
• Ecosystem: Next.js enhances React with features like server-side rendering (SSR) and static site generation (SSG). It simplifies deployment and scaling through its close integration with Vercel, the platform that maintains Next.js.
• Advantages: Built-in SSR and SSG, API routes for serverless functions, zero-config deployment, improved SEO and performance.

Performance

Blazor WebAssembly

• Performance: Runs .NET code directly in the browser via WebAssembly, providing a near-native performance once the application is loaded. The initial load time can be higher due to the size of the .NET runtime that needs to be downloaded.
• Optimization: Techniques like ahead-of-time (AOT) compilation and tree shaking are used to optimize performance.

ReactJS

• Performance: React’s virtual DOM diffing algorithm efficiently updates the UI. The performance is generally high but can vary based on how the application is implemented.
• Optimization: Code splitting, lazy loading, and memoization are commonly used to enhance performance in React applications.

NextJS

• Performance: Next.js excels in performance with its built-in features for SSR and SSG, which ensure faster initial page loads and better SEO. It also supports incremental static regeneration, allowing pages to be updated after the build process.
• Optimization: Automatic code splitting, image optimization, and caching strategies contribute to Next.js’s performance.

Development Experience

Blazor

• Development Experience: Offers a familiar development experience for .NET developers with features like dependency injection, a component-based architecture, and comprehensive tooling in Visual Studio.
• Tooling: Strong integration with Visual Studio, including debugging, IntelliSense, and project templates.
• Learning Curve: Easier for developers already familiar with C# and .NET.

ReactJS

• Development Experience: Highly flexible and modular. Developers can choose from a wide range of libraries and tools to set up their development environment.
• Tooling: Supported by tools like Create React App for project scaffolding, React DevTools for debugging, and extensive support in VS Code.
• Learning Curve: Requires learning JavaScript/TypeScript and React concepts like JSX, hooks, and state management.

NextJS

• Development Experience: Streamlined development with out-of-the-box support for SSR, SSG, and API routes. Provides a simplified setup and configuration process.
• Tooling: Excellent integration with Vercel for deployment and scalability, and built-in development server with hot module replacement.
• Learning Curve: Easier for developers familiar with React, but requires understanding of SSR/SSG concepts.

Deployment

Blazor

• Deployment: Can be deployed as static files to any static web host, such as GitHub Pages, Azure Static Web Apps, or AWS S3. Blazor Server apps can be deployed to any server that supports .NET.
• CI/CD: Integrates with Azure DevOps, GitHub Actions, and other CI/CD tools for automated deployments.

ReactJS

• Deployment: Typically deployed as static files to services like Vercel, Netlify, or traditional web servers. Can also be integrated with server-side frameworks like Express.js for more complex deployments.
• CI/CD: Supported by various CI/CD platforms, including GitHub Actions, Travis CI, and CircleCI.

NextJS

• Deployment: Optimized for deployment on Vercel, which supports both static and dynamic content seamlessly. Can also be deployed to other platforms like Netlify, AWS, or traditional servers.
• CI/CD: Vercel provides seamless CI/CD integration, automatically deploying updates when code is pushed to the repository.

Community and Support

Blazor

• Community: Growing community with strong backing from Microsoft. Resources include official documentation, Microsoft Learn, and community forums.
• Support: Enterprise-level support available from Microsoft, along with various third-party support options.

ReactJS

• Community: Massive and active community with numerous resources, tutorials, courses, and third-party libraries. Strong backing from Facebook.
• Support: Community-driven support with extensive online resources, plus commercial support available from various vendors.

NextJS

• Community: Rapidly growing community with strong backing from Vercel. Extensive documentation and tutorials are available.
• Support: Commercial support from Vercel, along with community-driven support and resources.

8. Deploying Your Blazor Application

To deploy your Blazor WebAssembly application, publish it using the following command:

dotnet publish -c Release

This command creates a dist folder in your project, which you can deploy to any static file host such as GitHub Pages, Azure Static Web Apps, or AWS S3.

9. Conclusion

Choosing between Blazor, ReactJS, and NextJS depends on your specific requirements, existing skill set, and the ecosystem you’re comfortable with. Blazor is an excellent choice for .NET developers looking to leverage their existing skills in web development. ReactJS offers unparalleled flexibility and a vast ecosystem, making it suitable for a wide range of applications. NextJS builds on ReactJS to provide powerful features for server-side rendering and static site generation, making it ideal for high-performance and SEO-friendly applications.