NestJs Questions

Mahesh pal

Score: 🔥 44

Beginner

Took 2 months

Programming Framework

NestJs

86%

Questions Attempted

15 / 15

Correct Answers

Incorrect Answers

Points Earned

🔥 13

Question 1

What is the purpose of dependency injection in NestJS?

To handle errors gracefully.
To manage database connections.
To provide a mechanism for creating and injecting dependencies into classes.
To define the application's routing logic.

Explanation:

Dependency injection is a design pattern where dependencies are 'injected' into a class rather than being directly instantiated within the class. This promotes modularity, testability, and reusability.

Question 2

How do you inject a provider from a different module in NestJS?

By using the @Inject() decorator and specifying the provider's class name.
By importing the module containing the provider into the module where you need it.
By creating a new instance of the provider using its constructor.
By accessing the global NestJS container.

Explanation:

To use a provider from a different module, you need to import the module that defines the provider into the module where you want to use it. This makes the provider available for injection within the importing module.

Question 3

What is the purpose of the @Get() decorator in NestJS?

Handles POST requests
Handles PUT requests
Handles DELETE requests
Handles GET requests

Explanation:

The @Get() decorator is used to mark a controller method as a handler for incoming HTTP GET requests. It specifies that the method should be invoked when a GET request is made to the associated route.

Question 4

What is the primary function of a module in NestJS?

To handle HTTP requests and responses.
To organize code into related units and manage dependencies.
To interact with databases and external APIs.
To define the application's entry point.

Explanation:

Modules in NestJS act as containers for other components like controllers, providers, and services. They help structure the application, making it more maintainable and promoting code reusability.

Question 5

What is a common use case for middleware in NestJS?

Generating database queries.
Rendering HTML templates.
Implementing authentication and authorization logic.
Defining API endpoints.

Explanation:

One of the most common use cases for middleware in NestJS is to handle authentication and authorization. Middleware provides a centralized location to verify user credentials, check permissions, and control access to protected routes.

Question 6

How can you access the currently logged-in user within your middleware in NestJS?

By injecting the Request object into the middleware function.
By using the user property of the Response object.
By accessing the req.user object, assuming you have an authentication middleware set up.
By querying the database directly within the middleware.

Explanation:

If you're using an authentication middleware in NestJS, it typically attaches the authenticated user object to the request object. You can access this user information within your middleware by referring to req.user.

Question 7

What is NOT a benefit of using Dependency Injection in NestJS?

Improved code testability.
Increased code coupling.
Enhanced code reusability.
Better maintainability of code.

Explanation:

Dependency Injection promotes loose coupling, not increased coupling. It allows components to depend on abstractions (interfaces) rather than concrete implementations.

Question 8

What is the primary purpose of exception handling in a NestJS backend application?

To gracefully handle and respond to unexpected errors during request processing.
To enforce strict data typing in controller methods.
To handle database migrations and schema changes.
To define middleware functions for request-response cycles.

Explanation:

Exception handling is crucial for preventing application crashes and providing meaningful error responses to clients when unexpected situations arise during request handling.

Question 9

Which of the following is NOT a valid HTTP method for defining routes in NestJS?

PUT
DELETE
RENDER
PATCH

Explanation:

NestJS uses standard HTTP methods for routing. RENDER is not a standard HTTP method; it's often associated with server-side templating engines.

Question 10

What is the role of the next() function in NestJS middleware?

To terminate the request-response cycle.
To pass control to the next middleware in the stack or the route handler.
To send a response back to the client.
To log information about the request.

Explanation:

The next() function is crucial for controlling the flow within middleware. Calling next() delegates the responsibility to the subsequent middleware in line or, if it's the last middleware, to the route handler.

Question 11

Which decorator is used to define a custom exception filter in NestJS?

@Injectable()
@Catch()
@Controller()
@Module()

Explanation:

The @Catch() decorator is specifically designed to mark a class as an exception filter, allowing it to handle specific exception types.

Question 12

What is a potential drawback of using singleton providers excessively in a large application?

Increased memory usage due to persistent instances.
Slower application startup time.
Difficulty in testing individual components.
All of the above.

Explanation:

While singletons offer benefits like shared state and reduced instantiation overhead, overusing them can lead to increased memory usage (as instances persist), slower startup (due to potential initialization chains), and challenges in isolating components during testing.

Question 13

What is the advantage of using built-in HTTP exception filters in NestJS?

They provide a streamlined way to handle common HTTP errors with predefined responses.
They allow you to bypass the need for exception handling altogether.
They are only applicable for database-related exceptions.
They are primarily used for handling authentication and authorization errors.

Explanation:

NestJS's built-in filters simplify error handling by providing ready-to-use responses for standard HTTP errors, reducing the need for repetitive code.

Question 14

After installing the NestJS CLI, what command is used to initiate a new NestJS project?

nest new project-name
nestjs create-app my-app
npm init nestjs-app
create-react-app my-nestjs-project

Explanation:

The nest new command followed by your desired project name is the standard way to start a new NestJS project using the CLI.

Question 15

What decorator is used for handling HTTP requests meant for updating resources?

@Post()
@Put()
@Delete()
@Patch()

Explanation:

The @Put() decorator marks a controller method for handling HTTP PUT requests, typically used for complete updates of existing resources.