For optimal performance when querying a large dataset in a NoSQL database, it is crucial to have proper ______ in place.
- Indexing
- Sharding
- Versioning
- Compression
For optimal performance when querying a large dataset in a NoSQL database, it is crucial to have proper indexing in place. Indexes help the database quickly locate and retrieve the data, reducing query response times.
You are developing a web application that needs to make API requests to a server on a different domain. How would you handle CORS to ensure that your web application can interact with the server without any issues?
- Set up a server-side proxy to forward requests to the other domain.
- Enable CORS on the server by adding appropriate headers to allow cross-origin requests.
- Use JSONP for making cross-domain requests.
- Disable CORS restrictions in the browser settings.
The correct approach is to enable CORS on the server by adding the appropriate headers that allow cross-origin requests. Option A can be a workaround, but it's not the best practice. Option C is an outdated method, and option D is not a recommended security practice.
How can prototype pollution vulnerabilities be mitigated in JavaScript applications?
- Avoid using third-party libraries
- Use strong typing for all variables
- Validate and sanitize user input
- Disable JavaScript prototypes
To mitigate prototype pollution vulnerabilities in JavaScript applications, it's crucial to validate and sanitize user input. This prevents malicious input from corrupting object prototypes. Avoiding third-party libraries and using strong typing are good practices but do not directly address prototype pollution. Disabling prototypes would break core JavaScript functionality.
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.
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.
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.
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.
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.
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.
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.