MongoDB, React, Node.js, and Express

What is the purpose of the MongoDB query API?

• To create tables
• To query and update documents in a collection
• To manage network access
• To generate JSON documents

Answer explanation

The MongoDB query API is used to query and update documents within a collection, allowing for data retrieval and manipulation.

How do you handle errors in React functional components?

• Using error boundaries
• Using try-catch blocks
• Using console.error()
• Using throw statements
• None

Answer explanation

Errors in React functional components can be handled using error boundaries, which catch JavaScript errors in their child component tree.

What's the primary use of middleware in Express?

• Data storage
• Error handling
• Execution of functions in the request-response cycle
• Frontend rendering

Answer explanation

Middleware in Express is primarily used for executing functions during the request-response cycle, allowing for tasks like logging, authentication, and error handling.

The Fetch API is only used to get the data from the server?

• True
• False
• None
• Sometimes true sometimes false

Answer explanation

The Fetch API can be used for various HTTP requests, including GET, POST, PUT, and DELETE, not just to retrieve data.

What is the role of the "Content-Type" header in a REST API request?

• It specifies the nature of the data in the body of the request.
• It defines the format of the request payload.
• It provides authentication credentials.
• It determines the cache control policy for the request.

Answer explanation

The "Content-Type" header in a REST API request specifies the nature of the data in the body of the request, indicating its format to the server.

How do you create a reusable component in React?

• Define a function component
• Define a class component
• Use a higher-order component
• Use a render prop
• None

Answer explanation

A reusable component in React can be created by defining a function component, which can then be used throughout the application.

What is the status code for a successful GET request in RESTful APIs?

• 200 OK
• 201 Created
• 204 No Content
• 404 Not Found
• None

Answer explanation

The status code 200 OK indicates a successful GET request, meaning the server successfully returned the requested resource.

How do you handle asynchronous data fetching in React functional components?

• Using useEffect
• Using useState
• Using componentDidMount
• Using componentDidUpdate

Answer explanation

Asynchronous data fetching in React functional components is typically handled using the useEffect hook, which allows you to perform side effects in function components.

How do you insert a new document into a collection in MongoDB?

• db.<collection_name>.insert()
• db.<collection_name>.newDocument()
• db.<collection_name>.add()
• db.<collection_name>.append()

Answer explanation

To insert a new document into a MongoDB collection, the 'db.<collection_name>.insert()' method is used.

What is the purpose of fs.readdirSync() in Node.js?

• Reads the contents of a directory synchronously
• Reads a file synchronously
• Removes a directory
• Renames a file
• None

Answer explanation

The 'fs.readdirSync()' method is used to read the contents of a directory synchronously in Node.js.