How can you access environment variables in a Node.js application using the process object?
- process.env.MY_VARIABLE
- Node.env.get("MY_VARIABLE")
- global.MY_VARIABLE
- env.process.MY_VARIABLE
In a Node.js application, you can access environment variables using process.env.MY_VARIABLE. The process object provides access to environment variables, and you access them using dot notation. The other options are incorrect syntax or reference non-existent objects.
The npm start command will run the script specified under the ______ key in the package.json file.
- start
- main
- scripts
- run
The npm start command runs the script specified under the "scripts" key in the package.json file. This key typically contains an object with various script names and their associated commands.
To enable debugging in an Express app, you should set the DEBUG environment variable to ______.
- TRUE
- FALSE
- 1
- 'express:debug'
To enable debugging in an Express app, you should set the DEBUG environment variable to 'express:debug'. This will provide detailed debugging information for your Express application.
You are building a chat application and need to implement a feature to upload and download files. How would you use streams in Node.js to handle file transfers efficiently between the client and the server?
- Read the entire file into memory on the server, then send it to the client in one go.
- Stream the file from the client to the server using a Readable stream, and then save it to disk on the server using a Writable stream.
- Use HTTP GET and POST requests to send files between the client and server.
- Compress the file before transferring it to reduce bandwidth usage.
To efficiently handle file transfers in a chat application, you should stream the file from the client to the server using a Readable stream and then save it to disk on the server using a Writable stream. This approach avoids loading the entire file into memory and is suitable for large file transfers.
To avoid callback hell while working with the fs module, you can use the ______ API, which returns promises.
- async
- await
- util.promisify
- Promise
To avoid callback hell when working with the fs module in Node.js, you can use the util.promisify API, which converts callback-based functions into promise-based functions. This allows you to work with promises and async/await syntax, improving code readability and maintainability.
Which of the following is true regarding the 'let' keyword in ES6+?
- let variables are hoisted to the top of their scope.
- let variables are block-scoped.
- let variables are globally scoped.
- let variables cannot be reassigned after declaration.
In ES6+, the let keyword is used to declare variables that are block-scoped, meaning they are limited to the block in which they are declared. Unlike var, let variables are not hoisted to the top of their scope. They can also be reassigned after declaration.
How can you handle errors in middleware in Express.js?
- Errors in middleware are automatically handled by Express.js and sent as a default error response.
- Use the next() function with an error object to pass it to an error handling middleware.
- Errors in middleware should be caught with a try...catch block inside the middleware function.
- Express.js does not support error handling in middleware.
In Express.js, errors in middleware can be handled by calling next(error) to pass the error to an error handling middleware. This allows for centralized error handling.
How can middleware functions modify the request and response objects in Express.js?
- Middleware functions can modify request and response objects directly.
- Middleware functions cannot modify request and response objects in Express.js.
- Middleware functions can only modify the request object, not the response object.
- Middleware functions can only modify the response object, not the request object.
Middleware functions in Express.js have access to the request and response objects, and they can modify these objects directly. This allows them to add, modify, or remove properties and headers, which is useful for various purposes like authentication, logging, and data transformation.
What happens if you omit the break statement in a switch statement in JavaScript?
- The program continues to execute the code in subsequent cases until it encounters a break statement or the end of the switch statement.
- An error is thrown, and the program crashes.
- The switch statement will exit immediately.
- The program ignores the switch statement entirely.
If you omit the break statement in a switch statement in JavaScript, the program will continue to execute the code in subsequent cases until it encounters a break statement or reaches the end of the switch statement. This behavior is known as "fall-through." The other options do not accurately describe the behavior of omitting the break statement.
You are building a content management system where the data structure is not uniform and may evolve over time. Which type of database would you choose, and what considerations should you have regarding schema design and querying efficiency?
- Graph Database
- NoSQL Database
- Relational Database
- Object-oriented Database
In this scenario, a NoSQL database would be the most suitable choice due to its flexibility in handling unstructured and evolving data. Considerations involve schema-less design, allowing data to change without strict schema constraints, and optimizing querying efficiency through appropriate indexing and data modeling.