You are building a RESTful API with Express to serve a mobile application. The mobile development team has asked for the ability to retrieve condensed responses to minimize data usage. How would you accommodate this request while maintaining the integrity of your API?
- Create separate endpoints for condensed and full responses.
- Use query parameters to allow clients to specify the response format.
- Disable compression to send smaller payloads.
- Use WebSocket instead of REST for real-time updates.
Using query parameters to allow clients to specify the response format is a common and RESTful approach to accommodating different client needs. Creating separate endpoints for each format can lead to redundancy and maintenance challenges. Disabling compression would likely increase, not decrease, data usage. Using WebSockets is for real-time communication and doesn't directly address response format concerns.
What are the best practices for error handling in a large-scale Node.js application?
- Avoiding error handling altogether for performance reasons.
- Using global error handlers for unhandled errors.
- Handling errors at the lowest level of code execution.
- Logging errors but not taking any action.
In large-scale Node.js applications, best practices for error handling include handling errors at the lowest level of code execution, close to where they occur. This improves code maintainability and makes it easier to trace the source of errors. Avoiding error handling for performance reasons is a bad practice. Using global error handlers is suitable for unhandled errors, but it's essential to handle errors at the source first. Simply logging errors without taking corrective action is incomplete error handling.
When a Promise is pending and neither fulfilled nor rejected, it is in the ________ state.
- awaiting
- undefined
- completed
- idle
When a Promise is pending and hasn't been resolved or rejected, it is in the "awaiting" state. This is the initial state of a Promise before it is settled.
When performing CRUD operations on a database, which operation can be the most expensive in terms of performance?
- Create
- Read
- Update
- Delete
Among CRUD operations, "Update" can often be the most expensive in terms of performance. This is because updating records may require the database to search for the existing record, make changes, and write the updated data back to disk, which can be resource-intensive. Read operations are typically less expensive.
How does indexing impact the performance of read and write operations in a database?
- It significantly slows down both read and write operations.
- It has no impact on read operations but speeds up write operations.
- It significantly speeds up read operations but has no impact on write operations.
- It significantly speeds up both read and write operations.
Indexing in a database can significantly speed up read operations because it allows the database system to quickly locate specific records. However, it can slightly slow down write operations because the database needs to update the index when new data is inserted or existing data is updated.
You are tasked with optimizing a large-scale application. How would identifying and managing closures help in optimizing the application's memory usage and performance?
- Closures have no impact on memory usage and performance
- Identifying and releasing unnecessary closures can reduce memory consumption and improve performance
- Closures should be created for all functions to improve memory management
- Increasing the use of closures will automatically optimize the application
Identifying and releasing unnecessary closures (option b) can indeed reduce memory consumption and improve performance in large-scale applications. Closures do impact memory usage, and creating too many unnecessary closures can lead to memory leaks and performance issues. Options a, c, and d do not accurately describe the role of closures in optimizing applications.
What happens to the prototype chain when using Object.create(null) in JavaScript?
- It creates an empty object with no prototype
- It inherits from the Object prototype
- It inherits from the null prototype
- It creates an object with its own prototype chain
Using Object.create(null) in JavaScript creates an empty object with no prototype, effectively removing it from the prototype chain. This is useful in scenarios where you want to create objects without inheriting any properties or methods from the default Object prototype.
When securing a web application using JWT, implementing ________ helps in mitigating the risk of token interception.
- Token expiration
- Strong encryption
- Public key authentication
- Rate limiting
When securing a web application with JWT (JSON Web Tokens), implementing strong encryption is crucial to mitigate the risk of token interception. Encryption ensures that the token's content remains confidential even if intercepted. Token expiration (Option 1) deals with token validity periods, while public key authentication (Option 3) is related to how JWT signatures are verified. Rate limiting (Option 4) is a measure to control access but doesn't directly address token interception.
What is the first line of defense against injection attacks in web applications?
- Using a web application firewall (WAF).
- Escaping user input before displaying it.
- Using strong authentication mechanisms.
- Regularly updating server software.
The first line of defense against injection attacks in web applications is to escape or sanitize user input before displaying it on web pages. This prevents malicious code from being executed, protecting against common injection attacks like SQL injection and cross-site scripting (XSS).
What considerations should be made when deciding between using a mock and a stub in a test case?
- The complexity of the test scenario
- The need for recording method calls
- The desire to control method behavior
- The size of the test data
When deciding between using a mock and a stub in a test case, considerations should include the complexity of the test scenario, as mocks are generally more complex than stubs. Recording method calls is a characteristic of mocks, and controlling method behavior is a characteristic of stubs. The size of the test data is typically not directly related to choosing between mocks and stubs.
You are tasked with implementing a secure authentication system for a web application. What considerations should you make to ensure the security of user credentials and session information?
- Store passwords in plain text
- Use a secure hashing algorithm for password storage
- Use HTTP for transmitting sensitive data
- Keep session tokens in local storage
To ensure the security of user credentials and session information, you should use a secure hashing algorithm (like bcrypt) to store passwords, not store them in plain text. Additionally, sensitive data should not be transmitted over HTTP, and session tokens should be stored securely (not in local storage, which is vulnerable to cross-site scripting attacks).
You are developing a Node.js application that should gracefully shut down when it receives a termination signal. How would you accomplish this using the process object?
- process.on('terminate', () => { /* Graceful shutdown code */ });
- process.kill('SIGTERM', process.pid);
- process.exit(0);
- process.handleTermination(() => { /* Graceful shutdown code */ });
To gracefully shut down a Node.js application upon receiving a termination signal, you should use process.on('terminate', () => { /* Graceful shutdown code */ });. This registers an event handler for the 'terminate' event. The other options either do not handle termination signals gracefully or are incorrect syntax.