You are developing a RESTful API using the http module and need to support CORS. How would you implement CORS headers to handle pre-flight requests in your HTTP server?
- Access-Control-Allow-Origin: *
- Access-Control-Allow-Origin: mydomain.com
- Access-Control-Allow-Origin: true
- Access-Control-Allow-Origin: false
To support CORS in your HTTP server, you should set the Access-Control-Allow-Origin header to the specific domain (e.g., mydomain.com) from which you want to allow requests. Using a wildcard (*) is less secure as it allows any domain, and using true or false is not the correct syntax for this header.
You are developing a media hosting platform where users can upload images and videos. How would you design the file storage and retrieval system to ensure high availability and low latency for users across the globe?
- Use a content delivery network (CDN) to cache and distribute media files to edge servers around the world.
- Store all media files on a single, centralized server to simplify management.
- Use a local file storage system for each region separately.
- Implement a peer-to-peer (P2P) system for users to share media directly.
To ensure high availability and low latency, using a CDN is the recommended approach. CDNs cache content on edge servers located across the globe, reducing the distance between users and the data they request. The other options may lead to latency issues and lower availability.
A common practice for improving error handling in Express.js is to centralize error handling using a ______.
- try-catch block
- catchError middleware
- globalErrorHandler middleware
- throw statement
A common practice for improving error handling in Express.js is to centralize error handling using a globalErrorHandler middleware. This middleware is responsible for handling errors that occur during request processing. While try-catch blocks can be used within routes, they don't centralize error handling, and catchError and throw are not standard middleware constructs in Express.js.
You are tasked with developing a system to read and process large files without consuming a lot of memory. How would you utilize streams in Node.js to efficiently read, process, and write the data?
- Use a Readable stream to read the file in chunks, process data asynchronously, and then write to a Writable stream.
- Read the entire file into memory, process it, and then write it back to disk.
- Use a synchronous file reading approach to minimize memory usage.
- Use a single callback function to read and process the entire file sequentially.
To efficiently process large files, you should use a Readable stream to read the file in chunks, process data asynchronously, and then write to a Writable stream. This approach minimizes memory usage and is ideal for handling large files in Node.js.
What is the significance of implementing Multi-Factor Authentication (MFA) in web applications?
- MFA adds an extra layer of security by requiring users to provide multiple forms of authentication, such as a password and a fingerprint scan.
- MFA simplifies the authentication process by reducing the number of login attempts.
- MFA is primarily used for tracking user behavior and analytics.
- MFA is only useful for protecting against physical security threats.
Implementing Multi-Factor Authentication (MFA) is significant in web applications as it adds an extra layer of security by requiring users to provide multiple forms of authentication, making it harder for unauthorized users to gain access even if they have the user's password. MFA enhances security and helps protect user accounts from various online threats.
In Express.js, to skip the remaining route callbacks and pass control to the next middleware function, you can call the ______ function.
- next()
- skip()
- pass()
- continue()
In Express.js, the next() function is used to skip the remaining route callbacks within a middleware function and pass control to the next middleware function in the chain. The other options are not valid functions for this purpose.
You need to develop a function that takes an array of numbers and returns a new array containing only the unique numbers. What approach would you use to filter out the duplicates?
- Using a for loop and checking uniqueness manually
- Using Array.prototype.filter() and a custom filter function
- Using Array.from(new Set(array))
- Using Array.prototype.reduce() with a custom accumulator function
To filter out duplicate numbers in an array, you can use Array.from(new Set(array)). This creates a Set from the array (which only keeps unique values) and then converts it back to an array. It's a concise and efficient approach for this task.
How can you allocate a buffer of a specified size without initializing it in Node.js?
- Buffer.alloc(size)
- Buffer.create(size)
- Buffer.new(size)
- Buffer.allocate(size)
To allocate a buffer of a specified size without initializing it in Node.js, you should use the Buffer.alloc(size) method. It allocates a new buffer of the given size and initializes it with zeros. The other options are not valid methods for achieving this.
Which caching strategy involves keeping the most recently used items?
- LRU (Least Recently Used)
- FIFO (First In, First Out)
- Random Replacement
- LFU (Least Frequently Used)
The caching strategy that involves keeping the most recently used items is called LRU, which stands for "Least Recently Used." In LRU caching, when the cache is full and needs to make space for a new item, it removes the least recently accessed item. This strategy is often used to maximize cache efficiency.
In a content delivery network (CDN), the process of distributing copies of files to multiple geographically dispersed servers is known as ______.
- Load Balancing
- Replication
- Caching
- Clustering
In a content delivery network (CDN), the process of distributing copies of files to multiple geographically dispersed servers is known as "Replication." This ensures that content is readily available to users from nearby servers, reducing latency and improving load times. Load balancing, caching, and clustering are related concepts but not specific to CDN replication.