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.
In Node.js, a duplex stream combines both readable and writable streams, and data can be written to and read from the '______' side.
- input
- output
- read
- write
In Node.js, a duplex stream combines both readable and writable streams, and data can be written to and read from the 'output' side. Duplex streams allow bidirectional data flow, making them suitable for tasks where data needs to be both read and written.
Which type of index is most suitable for searching through text-based content in a database?
- Full-Text Index
- B-Tree Index
- Hash Index
- Bitmap Index
Full-Text Index is the most suitable index type for searching through text-based content in a database. It is optimized for text search queries, allowing for efficient searching of words and phrases within text fields. B-Tree, Hash, and Bitmap indexes are more appropriate for different types of data and queries.
When chaining Promises, returning a non-Promise value from a .then() handler will cause the next .then() in the chain to receive a Promise resolved with that ________.
- Error
- Value
- Promise
- Rejection
When you return a non-Promise value (a regular value) from a .then() handler, the next .then() in the chain will receive a Promise that is resolved with that value. This allows you to pass values between Promise chain steps.
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.
How can the fs module handle reading very large files without loading the entire file into memory?
- By using the fs.readFile() method
- By using the fs.read() method
- By using the fs.createReadStream() method
- By using the fs.loadLargeFile() method
To handle reading very large files without loading the entire file into memory, you can use the fs.createReadStream() method. This method reads the file in small chunks, which allows you to process large files efficiently without consuming excessive memory. The other options do not provide a built-in mechanism for handling large files in this manner.
You are working on a project where multiple microservices need to interact with the same database. How would you manage model definitions and migrations in Sequelize to ensure consistency across services?
- Define and migrate models within each microservice separately.
- Share a single database schema across microservices.
- Utilize a central microservice to handle all model definitions and migrations.
- Don't use Sequelize in a microservices architecture.
In a microservices architecture, it's best to utilize a central microservice to handle all model definitions and migrations. This approach ensures consistency and avoids duplicating efforts. Options 1 and 2 can lead to inconsistencies and increased complexity, while option 4 is an extreme suggestion and may not be feasible.
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.