What implications does using synchronous fs methods have on the performance of a Node.js application?
- Synchronous methods improve performance
- Synchronous methods are non-blocking
- Synchronous methods may block the event loop
- Synchronous methods are recommended for I/O operations
Using synchronous fs methods can block the event loop in a Node.js application, leading to decreased concurrency and potentially poor performance. It's generally not recommended to use synchronous methods, especially for I/O operations, as they can disrupt the application's responsiveness.
In which scenario would the do-while loop be more appropriate than the while loop in JavaScript?
- When you want to execute the loop at least once before checking the condition.
- When you want to skip the loop execution based on a condition.
- When you want to perform a specific number of iterations.
- When you want to loop over an array.
The do-while loop in JavaScript is used when you want to execute the loop at least once before checking the condition. This is because the condition is checked after the loop body, ensuring that the loop body is executed at least once. The other options do not describe scenarios where a do-while loop is more appropriate.
You notice that the application behaves differently in the development and production environments. You suspect that it is due to a difference in the package versions being used. How would you investigate and resolve this discrepancy?
- Manually compare package.json files
- Use a dependency management tool like Yarn
- Check for environment-specific configuration files
- Use a lockfile like package-lock.json
To investigate and resolve differences in package versions, you should start by manually comparing the package.json files in your development and production environments. This will help you identify discrepancies in dependencies and their versions. Option (2) suggests using an alternative package manager, which may not directly address version discrepancies. Option (3) is relevant but doesn't specifically address package version differences. Option (4) is about lockfiles, which can help ensure consistent installations but won't directly highlight version discrepancies.
You are tasked with developing a real-time notification system in Node.js. Which feature of the Events module would be most beneficial in implementing this?
- event.emitOnce()
- event.removeAllListeners()
- event.once()
- event.removeListener()
In a real-time notification system, you would want to ensure that each notification is only sent once to the respective listeners. The event.once() method allows you to do this as it automatically removes the listener after it's been invoked once, ensuring efficient and clean handling of notifications. The other options are useful for managing listeners but do not guarantee a one-time notification.
You are developing an Express.js application that needs to validate user input on a specific route. How would you implement middleware to efficiently validate input for that route?
- Use the app.use method to add a middleware function to the specific route that performs input validation.
- Include the validation logic directly within the route handler function for the specific route.
- Define a separate middleware function and use app.use to apply it globally for all routes.
- Implement input validation as a part of the route's URL parameters.
To efficiently validate user input for a specific route in Express.js, you should create a dedicated middleware function using app.use and apply it only to the specific route in question. This approach keeps the route handler clean and separates concerns. The other options are less efficient or incorrect approaches.
The ______ event of the request object in the http module is emitted when the request body is being received.
- data
- request
- body
The data event of the request object in the http module is emitted when the request body is being received. This event allows you to handle incoming data in chunks, which is particularly useful for processing large request bodies without consuming excessive memory.
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.
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.
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.
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.