How does Non-Blocking I/O facilitate the development of scalable applications in Node.js?
- It allows multiple I/O operations to be executed concurrently without blocking the main thread.
- It forces all I/O operations to be executed sequentially, which improves predictability.
- It has no impact on application scalability.
- It reduces the number of I/O operations that can be performed concurrently.
Non-Blocking I/O in Node.js enables the execution of multiple I/O operations concurrently without blocking the main thread. This concurrency is essential for developing scalable applications that can handle numerous incoming requests simultaneously.
You are developing an Express.js application and you realize that some of the errors are not being caught by your error-handling middleware. What should you consider while debugging this issue?
- Check the order of middleware execution
- Increase the stack size of the Node.js process
- Disable error handling for those specific routes
- Increase the timeout for asynchronous operations
In Express.js, middleware functions are executed in the order they are defined. If some errors are not being caught by your error-handling middleware, it's crucial to check the order of middleware execution. Errors should be handled after they are thrown, so make sure your error-handling middleware comes after the routes that might throw errors.
Using the BigInt data type, you can represent integers larger than ______.
- 2^31 - 1
- 2^53 - 1
- 2^63 - 1
- 2^128 - 1
Using the BigInt data type in JavaScript, you can represent integers larger than 2^128 - 1. BigInts are not restricted by the usual 53-bit limit of regular JavaScript numbers (doubles), allowing you to work with much larger integers.
Which of the following can be considered as a performance bottleneck in a web application?
- High network latency
- Code comments
- Proper error handling
- Modular code structure
High network latency can be considered a performance bottleneck in a web application. Slow data transfer between the client and server due to network latency can significantly impact the application's performance. Code comments, proper error handling, and modular code structure, while important for code quality, are not typically performance bottlenecks.
You are developing an Express application that requires user authentication. How do you ensure that user credentials are secured, and sessions are managed effectively across different routes?
- Use a secure authentication library like Passport.js, store user credentials securely by hashing and salting passwords, and implement session management with the express-session middleware.
- Store user credentials in plain text for simplicity, use client-side storage for session management, and avoid encrypting sensitive data to reduce overhead.
- Implement a custom authentication mechanism using base64 encoding for user credentials, and manage sessions by storing them in a global JavaScript object.
- Use HTTP Basic Authentication for user login and manage sessions by storing user information in cookies without encryption.
To ensure secure user authentication and session management in an Express application, it's crucial to use a secure authentication library like Passport.js, securely store user credentials, and utilize a trusted session management middleware like express-session. Options 2, 3, and 4 are insecure and not recommended practices.
Why might a developer list a package as a devDependency instead of a dependency?
- A devDependency is needed only during development, not in production.
- A devDependency is automatically updated more frequently than a regular dependency.
- A devDependency reduces the overall bundle size of the application.
- A devDependency allows other developers to contribute to the project.
Developers list a package as a devDependency when it's required during development but not needed in production. This helps to keep the production build smaller and avoids unnecessary dependencies.
In Mocha, to perform cleanup activities after all the test cases in a suite have run, the ______ hook is used.
- after
- afterEach
- teardown
- suiteTeardown
In Mocha, the after hook is used to perform cleanup activities after all the test cases in a suite have run. It runs once after all test cases within the suite. The other options (afterEach, teardown, and suiteTeardown) represent different hook names or are not used for this specific purpose in Mocha.
When implementing file uploads in a serverless architecture, it is often beneficial to use ______ to handle file processing and transformations.
- AWS Lambda
- Docker Containers
- Kubernetes
- AWS S3
When implementing file uploads in a serverless architecture, it is often beneficial to use "AWS Lambda" to handle file processing and transformations. AWS Lambda allows you to execute code in response to events and can be triggered by file uploads. Docker containers and Kubernetes are containerization technologies, and AWS S3 is a storage service, but they are not typically used for serverless file processing.
When using the fs module to write data to a file, what considerations must be taken into account regarding concurrency?
- Node.js automatically handles concurrency
- Concurrency is not a concern when using fs
- Ensure proper locking mechanisms for concurrent writes
- Concurrency is only an issue with network operations
When working with the fs module, you must consider concurrency, especially when multiple processes or threads are writing to the same file simultaneously. It's important to implement proper locking mechanisms, such as file locking, to prevent data corruption. Node.js does not handle concurrency automatically.
Which object is primarily used to emit events in Node.js?
- Emitter
- EventEmitter
- EventObject
- EventHandler
In Node.js, the primary object used to emit events is EventEmitter. It's a built-in module that provides the core functionality for event-driven programming. Options A, C, and D are not the standard objects for emitting events in Node.js.