How can middleware be added to an Express application to process requests?
- Using the use() method
- Using the get() method
- Using the addMiddleware() function
- Using the handleRequest() method
Middleware can be added to an Express application using the use() method. This method allows you to specify middleware functions that can process requests in the order they are defined. The other options are not standard ways of adding middleware in Express.
How does the use of mocking and stubbing affect the isolation of unit tests?
- It increases isolation by replacing real dependencies with controlled substitutes.
- It reduces isolation by relying on actual dependencies.
- It has no effect on isolation.
- It increases isolation by running tests concurrently.
The use of mocking and stubbing in unit tests increases isolation by replacing real dependencies, such as external services or APIs, with controlled substitutes. This allows you to focus on testing the specific unit of code without worrying about the behavior of the real dependencies. Option (2) is incorrect because relying on actual dependencies doesn't create isolation in unit tests. Options (3) and (4) are also incorrect.
In a Cache-Aside strategy, when is the data loaded into the cache?
- Data is loaded into the cache on write operations.
- Data is loaded into the cache on read operations.
- Data is automatically loaded when the cache is initialized.
- Data is loaded into the cache periodically on a fixed schedule.
In a Cache-Aside strategy, data is not automatically loaded into the cache. Instead, it's loaded explicitly on read operations when an application requests the data.
What considerations should be made when implementing full-text search to ensure relevance and accuracy of search results?
- Stemming and lemmatization
- Exact matching
- Case sensitivity
- Shortening query length
When implementing full-text search, considerations should include stemming and lemmatization to handle variations of words (e.g., "run," "running," "ran"). This ensures that search results are more comprehensive and relevant. Exact matching alone may miss variations. Case sensitivity should be considered based on user requirements. Shortening query length may lead to the exclusion of important search terms.
You are assigned to optimize a Node.js application that is experiencing performance bottlenecks. The application heavily relies on reading and writing data to the file system. Which approach would be most effective in optimizing file system-related operations?
- Use asynchronous file system operations
- Increase CPU resources
- Optimize database queries
- Minimize network requests
In Node.js, using asynchronous file system operations (such as fs.readFile and fs.writeFile) is the most effective way to optimize file system-related operations. This prevents blocking the event loop and ensures that your application remains responsive while reading and writing files.
How can you determine the type of a variable in JavaScript?
- typeOf(variable)
- get.type(variable)
- variable->type
- typeof variable
In JavaScript, the typeof operator can be used to determine the type of a variable. The syntax is typeof variableName. The other options are not valid methods to determine the type in JavaScript.
Which grant type in OAuth 2.0 is suitable for machine-to-machine applications where a user is not involved?
- Client Credentials
- Authorization Code
- Implicit
- Resource Owner Password Credentials
The Client Credentials grant type in OAuth 2.0 is suitable for machine-to-machine (M2M) applications where there is no user involved. It allows an application to directly authenticate itself and obtain an access token. The other grant types involve user interaction and are not intended for M2M scenarios.
You are building an Express.js application where you have to route requests based on the subdomain. What approach would you take to implement this routing behavior?
- Use middleware to parse the subdomain and route accordingly
- Create separate Express.js applications for each subdomain
- Define subdomain-specific routes using regular expressions
- Use query parameters to determine the subdomain
To route requests based on the subdomain in Express.js, the most common approach is to use middleware (Option 1) that parses the subdomain from the request and then routes the request accordingly. This allows for flexibility and maintainability. Creating separate applications for each subdomain (Option 2) can lead to code duplication and complexity. Defining subdomain-specific routes using regular expressions (Option 3) can be error-prone and less maintainable. Using query parameters (Option 4) is not a common or recommended way to handle subdomain routing.
When designing a system with high-frequency Read operations, ______ the database can optimize performance by reducing the I/O operations on the database.
- Indexing
- Normalizing
- Caching
- Sharding
In systems with high-frequency Read operations, caching the database can optimize performance by reducing the I/O operations on the database server. Cached data can be quickly retrieved from memory, reducing the load on the underlying database.
How can the async/await syntax be used with error handling mechanisms, like try/catch, to handle asynchronous errors?
- Wrap the entire async function body in a try/catch block
- Use await inside a try/catch block for each individual asynchronous operation
- Use async without try/catch for handling errors
- Use await without try/catch for handling errors
To handle asynchronous errors with async/await, you should use a try/catch block around each individual await operation. This allows you to catch and handle errors for specific asynchronous operations within the async function. Option A would catch errors for the entire function, which might not provide fine-grained error handling. Options C and D are incorrect approaches for error handling with async/await.
Which of the following is true regarding object keys in JavaScript?
- Object keys must be unique within an object.
- Object keys can only be of type string.
- Object keys are case-sensitive.
- Object keys can only be integers.
Object keys in JavaScript are case-sensitive. This means that keys with different letter casing (e.g., 'key' and 'Key') are considered distinct in an object. The other options do not accurately describe the behavior of object keys.
You are designing a system with heavy Read and Update operations on the database. Which database design strategy would you adopt to balance the load and ensure data consistency?
- Sharding
- Replication
- Denormalization
- Indexing
In a scenario with heavy Read and Update operations, sharding is a database design strategy where you distribute the data across multiple servers or nodes. This helps balance the load and improve Read performance. Sharding ensures data consistency by managing data distribution and replication across shards. Replication (Option 2) can improve Read performance but doesn't address balancing the load directly. Denormalization (Option 3) can help with Reads but may complicate data consistency. Indexing (Option 4) helps with Read performance but doesn't balance the load.