ReactJS

 Here are some common ReactJS interview questions and answers:

Q1. What is ReactJS?

A1. ReactJS is an open-source, front-end JavaScript library developed by Facebook for building user interfaces or UI components. It follows the component based approach which helps in building reusable UI components.

Q2. What are the major features of ReactJS?

A2. Major features include:

- It uses VirtualDOM instead of RealDOM which is faster.

- It follows uni-directional data flow or one-way data binding.

- It uses reusable/composable UI components to develop the view.

- It is used for handling view layer only while Redux is used for state management.

- It uses server-side rendering for faster page load and better SEO.

Q3. What is JSX? 

A3. JSX is a HTML/XML-like syntax extension to JavaScript which is used in React for easily describing UI components. It is not valid JavaScript but gets transformed to JavaScript with transpilers like Babel. It makes code easy to read and write.

Q4. Difference between class and functional components

A4. Class components use ES6 class and render() method to return elements. Functional components use normal JavaScript functions to return elements. With hooks, functional components can now also use state and other features which were only for class components earlier.

Q5. What are state and props in React?

A5. State represents data maintained inside a component while props represent data passed from a parent component to a child component which is read-only for the receiving component. State data can be changed but triggers render while props are immutable.

ASP.NET Core

 Here are some more ASP.NET Core MVC interview questions:

Q1. What is view compilation in ASP.NET Core MVC and why is it useful?

A1. View compilation converts Razor views to C# classes during application startup. This avoids compilation overhead at runtime, improving response time. It is enabled by setting RazorCompileOnBuild to true.

Q2. How do you handle errors and exceptions in ASP.NET Core web APIs? 

A2. Using middleware such as app.UseExceptionHandler() to catch errors and return consistent error responses. We can also use filters like [ApiExplorer] for handling errors at controller action level.

Q3. What is model validation in ASP.NET Core MVC?

A3. Validating model properties based on validation attributes like [Required], [MaxLength] etc. applied to the model class. Validation is automatically triggered and error messages displayed in views using ValidationSummary, ValidationFor helpers.

Q4. How do you implement localization in ASP.NET Core MVC application?

A4. By configuring localization services in Startup. We define resource files per culture, configure localization middleware, call CreateLocalizationConvention to specify resource file locations. Use IStringLocalizer to access localized strings.

Q5. What are the differences between .NET Core and .NET Framework Runtime? 

A5. .NET Core is cross-platform, lightweight and supports more modern application scenarios like containers/microservices. .NET Framework supports older application models like WPF desktop apps, Windows workflows - limited to Windows.

Q6. What is middleware in ASP.NET Core and how does it work?

A6. Middleware are components that are part of the app pipeline that handle HTTP requests/responses. Multiple middleware are chained together using Use() in Configure() method. Pipeline flows through each middleware sequentially.

Q7. What are the main advantages of using ASP.NET Core over ASP.NET MVC?

A7. Cross-platform support, better performance, integration with modern client-side frameworks, lightweight and modular architecture due to middleware, configuration via C# code.

ASP.NET Core MVC || MVC

 Here are some additional ASP.NET Core MVC interview questions:

Q1. What is routing in ASP.NET Core MVC and how does it work?

A1. Routing is used to map incoming HTTP requests to particular MVC controller actions. The Configure() method in Startup.cs file adds endpoint routing middleware that maps request URLs to routing templates defined using attributes like [Route] and controllers.

Q2. How do you manage state in an ASP.NET Core application?

A2. ASP.NET Core is stateless by default. To manage state, we can use sessions by adding session middleware. State can also be stored in databases or external state cache like Redis. 

Q3. What is the file-based authorization policy in ASP.NET Core?

A3. It allows authorizing users against user roles defined in a JSON file rather than in app code. We create a JSON file mapping users to roles and configure the Authorization service to use the policy in Startup.cs.

Q4. How are model bindings used in ASP.NET Core MVC?

A4. Model binding automatically maps form data and route data from an HTTP request to parameters in a controller action. We just need to define the parameter name same as input field in a form or route parameter.

Q5. What is view composition in ASP.NET Core MVC?

A5. Building a view using both a main view and partial views defined in separate Razor view files. The main view can render HTML sections defined in partial views using @await Html.PartialAsync() method.

Q6. How do you serve static files in ASP.NET Core web apps?

A6. Using built-in middleware by configuring it through methods like app.UseStaticFiles() in Startup.cs. We define a static file path, set caching headers for static files etc.

Q7. How do you implement logging in ASP.NET Core apps?

A7. Using ILogger interface injected into classes needing logging. Log messages written through ILogger will be directed to logging providers configured in Startup - like console, debug, file, Azure App Insights etc.

ASP.NET Core MVC || Core

 Here are some additional ASP.NET Core MVC interview questions and answers:

Q1. What is Razor in ASP.NET Core MVC?

A1. Razor is a view engine for rendering views. It allows you to mix C# or Visual Basic code with HTML markup in Razor View (.cshtml file) to build UI.

Q2. What are Tag Helpers in ASP.NET Core MVC?

A2. Tag Helpers allow you to add server-side logic to existing HTML tags using attributes designed for that specific tag. They are processed on the server before any client-side frameworks like React or Angular get them.

Q3. How do you handle security in ASP.NET Core MVC applications?  

A3. Some ways to handle security include:

- Authentication - Identity library, Azure AD, OAuth/OpenID 

- Authorization - Role-based or policy-based authorization

- HTTPS

- CORS

- Input validation

Q4. What is caching? How can we implement caching in ASP.NET Core?

A4. Caching is storing data/page output temporarily so that future requests can be served faster. We can implement in-memory caching using IMemoryCache interface or a distributed cache like Redis. The data has an expiration period and gets invalidated after that.

Q5. How do you configure linking between MVC views and actions?

A5. Using attribute routing to provide named routes like [Route("[controller]/[action]")]. We generate links using these named routes with Url.Action() or <a asp-action="">

Q6. What is JSON serialization and how do you implement it in ASP.NET Core?

A6. Converting a .NET object to JSON format. We can use JsonSerializer class or in ASP.NET Core, adding [ApiController] attribute handles serialization automatically using System.Text.Json library.

Q7. What is view injection in ASP.NET Core MVC?

A7. Dependency injecting a view component into a view via the @inject directive so that we can call methods on that injected class directly from the view.

ASP.NET Core MVC

 Here are some common ASP.NET Core MVC interview questions and answers:

Q1. What is ASP.NET Core MVC?

A1. ASP.NET Core MVC is a web framework from Microsoft that implements the model-view-controller (MVC) pattern. It allows you to build web applications and APIs using .NET Core.

Q2. What are some key features of ASP.NET Core MVC?

A2. Key features include:

- Lightweight and high performance

- Built on .NET Core which runs on Windows, MacOS and Linux

- Integrated support for client-side frameworks like Angular, React and Bootstrap

- Flexible configuration and routing 

- Dependency injection

- Razor view engine to build UI using C# and HTML

Q3. What is the role of models, views and controllers in ASP.NET Core MVC?

A3. Models represent the application data and business logic. Views are responsible for the UI to interact with users. Controllers handle requests from clients, interact with models and pass data to views.

Q4. How is ASP.NET Core different from ASP.NET MVC?

A4. ASP.NET Core is a re-architected version of ASP.NET and runs on .NET Core. It is cross-platform, faster and more flexible. ASP.NET MVC runs on the traditional .NET Framework so it is Windows-only.

Q5. What is dependency injection in ASP.NET Core and why is it useful?  

A5. Dependency injection (DI) is a technique to achieve inversion of control between classes and their dependencies. In ASP.NET Core, you can use DI to configure services and inject them into controllers/other classes in your application startup. This makes your code loosely coupled.

Q6. How do you configure middleware in ASP.NET Core?

A6. Using IApplicationBuilder interface, which provides methods like Use(), Run() etc. to configure the HTTP pipeline with middleware components. The pipeline is configured in Startup.cs file in the Configure() method.

Q7. What is view models in ASP.NET Core MVC?

A7. View models are classes defined specifically to pass data from controllers to views. They only contain data needed for a view and help to maintain separation of concerns.

Q8. How do you manage client-side packages in ASP.NET Core?

A8. Using Node Services to execute Node.js command line interfaces to install packages like Bootstrap, jQuery etc. Bower can also be used to manage client-side libraries.

How do I clear the component cache in Visual Studio? || Component Model Cache || AppData

Clearing the Visual Studio Component Cache can be useful in resolving certain issues related to the IDE. The component cache is a collection of assemblies, resources, and other files that Visual Studio uses to improve performance. If this cache becomes corrupted or outdated, you may encounter various problems such as slow performance, build errors, or unexpected behavior.

Here are the general steps to clear the Visual Studio Component Cache:

1. Close Visual Studio:

Make sure Visual Studio is completely closed before you proceed.

2. Delete the ComponentModelCache folder:

The component cache is typically located in the following directory:

%USERPROFILE%\AppData\Local\Microsoft\VisualStudio\<Visual Studio Version>\ComponentModelCache

Replace <Visual Studio Version> with the version number of your Visual Studio installation (e.g., 2019).

Delete the entire ComponentModelCache folder.

3. Clear the Temporary ASP.NET Files:

If you're working with ASP.NET projects, you might also want to clear the Temporary ASP.NET Files. The path is typically:

%USERPROFILE%\AppData\Local\Temp\Temporary ASP.NET Files

Delete the contents of the Temporary ASP.NET Files folder.

4. Restart Visual Studio:

After deleting the cache folders, restart Visual Studio. The IDE will rebuild the cache as needed.

5. Rebuild your solution:

Open your solution in Visual Studio and try rebuilding it to see if the issues are resolved.

Keep in mind that manually deleting cache folders is generally safe and can help resolve certain issues, but it's always a good idea to back up your projects or important files before making any changes.