In a Write-Around caching strategy, the data is written directly to the ______, bypassing the cache.
- Disk
- Server
- Database
- RAM
In a Write-Around caching strategy, the data is written directly to the database, bypassing the cache. This strategy is useful for data that doesn't need to be immediately cached, such as rarely accessed data or large files.
In JavaScript, objects created using object literal syntax are instances of ______.
- Object
- Function
- Prototype
- Class
In JavaScript, objects created using object literal syntax are instances of the Object constructor. This means they inherit properties and methods from the Object prototype.
In Express.js, to catch errors from a promise within a route, the next function should be called with the ______ as an argument.
- error
- promise
- err
- next
In Express.js, to catch errors from a promise within a route, the next function should be called with the err as an argument. This allows Express.js to recognize it as an error-handling middleware. Passing error, promise, or next itself would not trigger the error handling mechanism in Express.js.
You are developing a real-time analytics dashboard that requires aggregation of data from multiple tables. How can you optimize the queries to ensure minimum latency in displaying the results?
- Use caching mechanisms
- Opt for synchronous queries to ensure real-time data
- Optimize database indexes
- Use a single table to store all data
To ensure minimum latency in a real-time analytics dashboard, using caching mechanisms is essential. Caching can store frequently used aggregated data and serve it quickly, reducing the need for complex queries. Options B and D do not align with best practices for real-time analytics. Option C is a good practice but not as directly related to real-time performance as caching.
What is the significance of the call(), apply(), and bind() methods in JavaScript functions?
- They are used for declaring global variables.
- They enable asynchronous execution of functions.
- They manipulate the DOM.
- They facilitate the manipulation of function context and parameter passing.
call(), apply(), and bind() are methods in JavaScript used to manipulate the context in which a function is executed and to pass arguments to functions. They are commonly used in scenarios like setting the value of 'this' in a function and passing arguments dynamically. None of the other options correctly describe their purpose.
What is the first argument typically passed to a callback function in Node.js to handle errors?
- result
- data
- error
- callback
The first argument typically passed to a callback function in Node.js to handle errors is error. This argument holds information about any errors that may have occurred during the asynchronous operation. The other options (result, data, and callback) are used for different purposes in callback functions.
Which of the following ESLint rules enforces consistent indentation in your code?
- no-console
- indent
- semi
- no-unused-vars
The indent rule in ESLint enforces consistent indentation in your code. It helps ensure that your code is properly formatted and readable by specifying the expected indentation style. The other options are for different rules, such as preventing the use of console, enforcing semicolons, or catching unused variables.
How can you remove a listener from an event using the Events module in Node.js?
- event.removeListener(event, listener)
- event.remove(listener)
- event.off(event, listener)
- listener.remove(event)
To remove a listener from an event using the Events module in Node.js, you should use the event.removeListener(event, listener) method. This method takes the event name and the listener function as arguments and removes the specified listener from the event. The other options are not valid methods for removing listeners.
What happens to the Event Loop when the callback queue and the task queue are both not empty?
- It suspends the Event Loop until both queues are empty.
- It processes callbacks from the callback queue before tasks from the task queue.
- It processes tasks from the task queue before callbacks from the callback queue.
- It randomly selects items to process from both queues.
When both the callback queue and the task queue are not empty, the Event Loop in Node.js follows a specific order. It first processes callbacks from the callback queue before moving to tasks from the task queue. This order ensures that callback functions, which often include I/O operations, are handled promptly.
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.