In Node.js, what is the purpose of the process.on('uncaughtException', handler) method?
- To catch exceptions and continue program execution
- To exit the Node.js process on any unhandled exception
- To display uncaught exceptions in the console
- To handle exceptions within a specific function
The process.on('uncaughtException', handler) method in Node.js is used to capture unhandled exceptions and prevent the Node.js process from crashing. It allows you to specify a custom handler function to handle these exceptions gracefully. The other options do not accurately describe the purpose of this method.
In a NoSQL database like MongoDB, how are schemas defined and enforced?
- Schemas are strictly enforced before data insertion
- Schemas are defined using SQL
- Schemas are flexible and can evolve with data
- Schemas are predefined and cannot change
In NoSQL databases like MongoDB, schemas are flexible and can evolve with data. There's no strict enforcement of schemas before data insertion, allowing for schema-less data storage. This flexibility is one of the key features of NoSQL databases, making them suitable for handling unstructured or semi-structured data.
How does JavaScript’s prototypal inheritance differ from classical inheritance models?
- JavaScript uses delegation-based inheritance, where objects inherit from other objects directly, not from classes.
- JavaScript uses class-based inheritance like many other programming languages.
- JavaScript's inheritance is more rigid and less flexible compared to classical models.
- JavaScript's inheritance is limited to only built-in objects.
JavaScript's prototypal inheritance differs from classical inheritance models by using delegation-based inheritance. Instead of inheriting from classes, objects inherit directly from other objects, which is more flexible and dynamic.
You are working on a project where you need to load different modules based on user actions dynamically. What approach should you take to load the modules only when necessary?
- Use synchronous module loading.
- Use Webpack to bundle all modules upfront.
- Employ dynamic import statements.
- Load all modules at application startup.
To load modules dynamically based on user actions, you should employ dynamic import statements (Option c). Dynamic imports allow you to load modules asynchronously and only when they are needed, improving the efficiency of your application. Synchronous loading (Option a) and loading all modules upfront (Option d) are counterproductive for this scenario. While Webpack bundling (Option b) can be useful for other purposes, it doesn't address the need for dynamic loading.
You are tasked with developing a file upload module in Node.js. The files uploaded by users are binary data. How would you handle the incoming binary data to ensure data integrity and optimal resource utilization?
- Use streams to handle and process binary data in chunks
- Read the entire binary data into memory before processing
- Convert binary data to hexadecimal for storage
- Store binary data in a JSON format
To ensure data integrity and optimal resource utilization when handling binary data in a file upload module, it's best to use streams to handle and process binary data in chunks. This approach minimizes memory usage and ensures data integrity. Reading the entire binary data into memory is not efficient, and the other options are not suitable for storing binary data.
You are tasked with evolving the schema of a critical, high-traffic database while minimizing downtime and data inconsistency. What strategies would you employ to safely apply schema migrations?
- Use database migration tools with rollback support.
- Apply schema changes during off-peak hours.
- Utilize database versioning and backward-compatible changes.
- Pause the database for maintenance during schema updates.
Option (1) is a common approach as it allows you to apply changes with rollback capabilities. Option (2) is valid to minimize the impact on users. Option (3) is also important, using versioning and backward-compatible changes ensures a smoother transition. Option (4) is typically not recommended, as it causes downtime.
Can you modify the package.json file after it has been created by the npm init command?
- Yes, but only with admin privileges
- No, it's read-only
- Yes, it can be edited anytime
- Yes, but only during project initialization
Yes, you can modify the package.json file after it has been created by the npm init command. It's a JSON configuration file that stores information about your project, and you can update it to add dependencies, scripts, and other project-related settings. It's a fundamental part of managing Node.js projects.
In Express.js, how can you handle errors occurring in asynchronous code within a route handler?
- try-catch
- next(error)
- return error;
- res.error(error)
In Express.js, you can handle errors occurring in asynchronous code within a route handler by calling next(error). This passes the error to the error-handling middleware or the default error handler, allowing you to centralize error handling. Using a try-catch block won't catch asynchronous errors, and the other options are not standard practices for error handling in Express.js.
Which type of testing focuses on verifying the functionality of individual components in isolation?
- Unit Testing
- Integration Testing
- System Testing
- Performance Testing
Unit Testing focuses on verifying the functionality of individual components (or units) in isolation. It helps ensure that each component works correctly on its own.
Which of the following is the correct syntax for destructuring an array in JavaScript?
- let [x, y] = [1, 2];
- let {x, y} = [1, 2];
- let (x, y) = [1, 2];
- let x = [1, 2];
Destructuring an array in JavaScript is done using square brackets []. The correct syntax is let [x, y] = [1, 2];. The other options are either for object destructuring or use incorrect syntax.