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.
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.
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.
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 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.
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.
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.
What is the outcome of using closures regarding variable scope and lifetime in JavaScript?
- Variables declared in a closure have global scope.
- Variables declared in a closure are accessible only within the closure itself.
- Variables declared in a closure have the same scope as variables declared in the outer function.
- Variables declared in a closure have function scope.
Closures in JavaScript have function scope, meaning variables declared within a closure are accessible only within that closure. They do not have global scope and are not directly accessible from outside the closure.
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.
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 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.
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.