The spread operator can be used to merge two ______ into a new one, combining their properties.
- Arrays
- Objects
- Strings
- Functions
The spread operator can be used to merge two "Objects" into a new one, combining their properties. It's a useful way to create a new object with properties from multiple source objects.
You are creating a function that accepts an arbitrary number of arguments and returns an array of those arguments. How would you use the rest operator in this scenario to collect all the passed arguments?
- (function(...args) { return args; })
- (function(args) { return args; })
- (function([...args]) { return args; })
- (function() { return ...args; })
To create a function that accepts an arbitrary number of arguments and returns an array of those arguments, you would use the rest parameter syntax (...args) in the function's parameter list. This syntax collects all the passed arguments into an array named args. The other options are either incorrect or do not use the rest operator correctly.
What is the significance of the 'backpressure' concept in streams in Node.js?
- Backpressure ensures that data is not lost when reading from or writing to a stream.
- Backpressure prevents data from being written to a stream.
- Backpressure is a measure of stream performance.
- Backpressure is used to close streams automatically.
The significance of 'backpressure' in streams is that it ensures that data is not lost when reading from or writing to a stream. It allows the consumer of data to control the rate of data flow, preventing buffer overflow and resource exhaustion. The other options do not accurately describe the concept of 'backpressure.'
How can specific error handlers be created to respond to different error types in Express.js?
- Use the try...catch block
- Define multiple catch blocks
- Use the app.error() middleware
- Utilize the next(err) function with custom error classes
In Express.js, specific error handlers for different error types can be created by utilizing the next(err) function with custom error classes. This allows you to define error-handling middleware that can respond to specific error types based on their custom classes. The other options are not typically used for handling specific error types in Express.js.
Which of the following accurately describes Non-Blocking I/O in Node.js?
- I/O operations that block the main thread
- I/O operations that execute concurrently
- I/O operations that are not supported in Node.js
- I/O operations that must be executed in a callback
Non-Blocking I/O in Node.js refers to I/O operations that execute concurrently without blocking the main thread. It allows Node.js to perform multiple I/O operations without waiting for each operation to complete. The other options describe blocking I/O or do not accurately describe non-blocking I/O.
You are designing a database schema for an e-commerce application, focusing on optimal performance. How would you design the schema and optimize queries to minimize the load on the database?
- Use a denormalized schema
- Implement proper indexing
- Utilize stored procedures for all queries
- Avoid using primary keys
To minimize the load on the database in an e-commerce application, implementing proper indexing is crucial. Indexes allow the database to efficiently retrieve data. Denormalized schemas can lead to redundancy and maintenance challenges. While stored procedures can be useful, they are not the primary means of optimizing queries. Avoiding primary keys is not recommended; they are essential for data integrity.
Which fs method would you use to read the contents of a directory?
- fs.readdir()
- fs.read()
- fs.readDir()
- fs.listDirectory()
To read the contents of a directory in Node.js, you should use the fs.readdir() method. It returns an array of all the file and directory names in the specified directory. The other options are not valid fs methods for this purpose.
You are designing a real-time data processing system where data needs to be transformed before being sent to another service. How would you implement streams in Node.js to ensure smooth data transformation and transmission?
- Use a single function to transform data and send it directly to the service.
- Implement a Readable stream to receive data, transform it with a Transform stream, and then pipe it to a Writable stream that sends it to the service.
- Store all incoming data in memory, transform it, and then send it to the service.
- Use asynchronous callbacks to process data and send it to the service as it arrives.
In a real-time data processing system, you should implement streams. Use a Readable stream to receive data, transform it with a Transform stream, and then pipe it to a Writable stream that sends it to the service. This approach allows for smooth data transformation and transmission without storing large amounts of data in memory.
What is the difference between process.nextTick() and setImmediate() in Node.js?
- process.nextTick() executes callbacks before any I/O events. setImmediate() executes callbacks after I/O events.
- process.nextTick() is used for synchronous execution, while setImmediate() is used for asynchronous execution.
- process.nextTick() is a browser API, and setImmediate() is a Node.js API.
- process.nextTick() has a higher priority than setImmediate().
The primary difference between process.nextTick() and setImmediate() in Node.js is their timing. process.nextTick() executes callbacks before any I/O events, allowing you to schedule code to run immediately after the current operation, while setImmediate() executes callbacks after the current I/O event loop phase, providing a smoother event loop. The other options do not accurately describe the difference.
When destructuring arrays, using the rest operator will result in a new array containing the ______ elements.
- First
- Last
- Middle
- Remaining
When destructuring arrays using the rest operator, it will result in a new array containing the "Remaining" elements. The rest operator collects the remaining elements of an array into a new array.
Your application allows users to upload and share documents. You need to implement a solution to scan uploaded documents for malicious content. What considerations and strategies would you employ to ensure the security of the uploaded files?
- Utilize antivirus software to scan files on the server.
- Implement a content filtering system with regular expression checks.
- Use machine learning-based content analysis to detect malicious content.
- Skip content scanning to improve performance.
Employing machine learning-based content analysis is an effective way to detect malicious content in uploaded files. It can adapt and improve over time, providing better security. The other options are less robust and may not adequately protect against malicious uploads.
Which part of the semantic versioning number (e.g. 1.2.3) is incremented for backwards-compatible bug fixes?
- Major version
- Minor version
- Patch version
- Build version
In SemVer, the 'patch' version is incremented for backwards-compatible bug fixes. This is done to indicate that changes made in this version are intended to address bugs without introducing breaking changes or new features.