You are developing a real-time chat application in Node.js. How would you design the application to handle a high number of simultaneous connections without degrading performance, considering the nature of the Event Loop and Non-Blocking I/O?
- Use worker threads to offload CPU-intensive tasks.
- Utilize Node.js cluster module for load balancing.
- Implement microservices architecture for scalability.
- Increase the Event Loop's thread pool size.
To handle a high number of simultaneous connections without degrading performance in Node.js, you can use the cluster module, which allows you to create multiple child processes (workers) to distribute the load efficiently. Options a and c do not directly address the Node.js Event Loop's nature, and option d is not a recommended approach as it may lead to thread contention.
You are developing a high-traffic RESTful API with Express. How would you design the architecture to ensure optimal performance, scalability, and maintainability?
- Use a single server instance for simplicity.
- Implement a microservices architecture with multiple small services.
- Rely solely on client-side caching to reduce server load.
- Don't worry about code structure; focus on hardware upgrades for scalability.
Implementing a microservices architecture with multiple small services allows for optimal performance, scalability, and maintainability. Using a single server instance can become a bottleneck in high-traffic scenarios. Relying solely on client-side caching doesn't address server-side performance and scalability issues. Neglecting code structure and relying on hardware upgrades is not a best practice for maintainability.
How can you import a specific item from a module in ES6+?
- import { item } from 'module';
- import 'module' item;
- import item from 'module';
- include { item } from 'module';
In ES6+ JavaScript, you can import a specific item from a module using the syntax import { item } from 'module';. This allows you to selectively import only the items you need from a module. The other options are not valid import syntax in ES6+.
What are the implications of choosing an improper data type for a field in a database schema on storage and performance?
- Increased storage space, slower queries
- Decreased storage space, faster queries
- Improved data integrity
- No impact on storage or performance
Choosing an improper data type can lead to increased storage space and slower queries. For example, using a large data type for a small piece of data wastes space and may result in more I/O operations, slowing down queries. It's crucial to choose appropriate data types to optimize storage and performance.
You need to build a middleware that performs multiple operations asynchronously before passing control to the next middleware. How can you ensure that your middleware handles errors effectively and does not hang the application?
- Implement error handling within the middleware using try-catch blocks and call the next middleware with an error parameter if an error occurs. Use next(err) to propagate the error to Express's default error handler.
- Avoid error handling in middleware to improve performance, rely on Express's default error handling, and use a timeout to prevent the middleware from hanging indefinitely.
- Use callbacks instead of promises or async/await for asynchronous operations within the middleware to avoid potential errors, and rely on external tools to monitor and handle errors.
- Use the process.exit() method to terminate the application if an error occurs within the middleware to prevent it from hanging.
To ensure that a middleware handles errors effectively and does not hang the application, it's best practice to implement error handling within the middleware itself using try-catch blocks and call next(err) to propagate the error to Express's default error handler. Option 2 is not recommended as it bypasses proper error handling, and options 3 and 4 are unconventional and may cause issues.
The spread operator can effectively be used to create a shallow ______ of an object or an array.
- Copy
- Clone
- Reference
- Duplicate
The spread operator can effectively be used to create a shallow "Clone" of an object or an array. When you use the spread operator, it creates a new object or array with the same values as the original, but it is a separate entity in memory. This is known as a shallow clone.
When handling errors in an async function, if an error is not caught within the function, it will cause the returned Promise to be in a ________ state.
- Pending
- Fulfilled
- Rejected
- Completed
When an uncaught error occurs in an async function, the returned Promise will be in a "Rejected" state. In the Promise lifecycle, it can start as "Pending," move to "Fulfilled" upon success, or "Rejected" upon an error.
Why would you use the global object to store data in a Node.js application?
- To share data between different Node.js modules.
- To encapsulate data and prevent it from being accessed globally.
- To improve application performance by reducing memory usage.
- To ensure data persistence across application runs.
The global object in Node.js can be used to store data that needs to be shared between different Node.js modules. It acts as a global namespace for variables and allows you to share data across different parts of your application. The other options do not accurately describe the common use case for the global object.
How does semantic versioning handle pre-release versions and build metadata?
- Pre-release versions are denoted with a hyphen and can include additional labels and numbers. Build metadata is indicated with a plus sign.
- Pre-release versions use square brackets to specify additional labels, and build metadata uses parentheses.
- Pre-release versions are marked with a plus sign, and build metadata is indicated with a hyphen.
- Pre-release versions are not supported in semantic versioning.
Semantic versioning allows pre-release versions to be denoted with a hyphen, followed by additional labels and numbers, and build metadata is indicated with a plus sign. This is essential for managing versions during development and testing phases.
Which data type in JavaScript can be used to store a sequence of characters?
- char
- sequence
- string
- text
In JavaScript, the string data type is used to store a sequence of characters. The char data type doesn't exist in JavaScript, and neither sequence nor text are valid data types for this purpose.