What are the implications of choosing an improper data type for a field in a database schema on storage and performance?
- Increased storage space, slower queries
- Decreased storage space, faster queries
- Improved data integrity
- No impact on storage or performance
Choosing an improper data type can lead to increased storage space and slower queries. For example, using a large data type for a small piece of data wastes space and may result in more I/O operations, slowing down queries. It's crucial to choose appropriate data types to optimize storage and performance.
You need to build a middleware that performs multiple operations asynchronously before passing control to the next middleware. How can you ensure that your middleware handles errors effectively and does not hang the application?
- Implement error handling within the middleware using try-catch blocks and call the next middleware with an error parameter if an error occurs. Use next(err) to propagate the error to Express's default error handler.
- Avoid error handling in middleware to improve performance, rely on Express's default error handling, and use a timeout to prevent the middleware from hanging indefinitely.
- Use callbacks instead of promises or async/await for asynchronous operations within the middleware to avoid potential errors, and rely on external tools to monitor and handle errors.
- Use the process.exit() method to terminate the application if an error occurs within the middleware to prevent it from hanging.
To ensure that a middleware handles errors effectively and does not hang the application, it's best practice to implement error handling within the middleware itself using try-catch blocks and call next(err) to propagate the error to Express's default error handler. Option 2 is not recommended as it bypasses proper error handling, and options 3 and 4 are unconventional and may cause issues.
The spread operator can effectively be used to create a shallow ______ of an object or an array.
- Copy
- Clone
- Reference
- Duplicate
The spread operator can effectively be used to create a shallow "Clone" of an object or an array. When you use the spread operator, it creates a new object or array with the same values as the original, but it is a separate entity in memory. This is known as a shallow clone.
You are managing a project with multiple dependencies, and you want to ensure that upgrading a dependency doesn't break the project due to API changes. How would you specify the version numbers of the dependencies in the package.json file?
- ^1.0.0
- ~1.0.0
- 1.0.0
- 1.x.x
To ensure that only patch-level changes are allowed for your dependencies, you should use the ~ (tilde) prefix. This will allow for bug fixes (patch versions) but prevent breaking changes (minor or major versions).
The 'highWaterMark' option in Node.js streams denotes the ______ of the internal buffer.
- size
- rate
- capacity
- length
In Node.js streams, the 'highWaterMark' option denotes the capacity of the internal buffer. This value determines how much data the stream can buffer before it starts to pause the data source.
Where should you ideally store your static files like images, CSS, and JavaScript in an Express.js project?
- In the project root directory
- In a dedicated static directory
- Inside the node_modules directory
- In a separate database
In an Express.js project, it's a best practice to store your static files like images, CSS, and JavaScript in a dedicated static directory. This helps organize your project and makes it clear which files are intended to be served statically. Storing them in the project root, node_modules, or a database is not a recommended practice for serving static files.
In what way does the Event Loop affect the performance of a Node.js application?
- It can improve performance by handling asynchronous operations efficiently.
- It slows down the application by blocking all I/O operations.
- It has no impact on performance.
- It can only handle synchronous operations.
The Event Loop in Node.js plays a crucial role in improving performance by efficiently handling asynchronous operations. It allows Node.js to execute non-blocking code, ensuring that the application remains responsive and can handle multiple concurrent requests without getting blocked.
Which of the following is the primary role of middleware in Express.js?
- Handling client-side routing
- Handling server-side routing
- Managing HTTP requests and responses
- Creating database schemas
The primary role of middleware in Express.js is to manage HTTP requests and responses. Middleware functions are executed in the order they are defined in the Express application and can perform various tasks such as authentication, logging, and modifying request/response objects. They play a crucial role in the request/response cycle.
Which keyword is used to export multiple things from a module in JavaScript?
- import
- export
- require
- module
In JavaScript, the export keyword is used to export multiple things from a module. It allows you to specify which functions, objects, or variables should be accessible from outside the module. The import keyword is used for importing from modules, not exporting. The require and module keywords are used in CommonJS, a different module system.
How does JavaScript handle circular dependencies between modules?
- JavaScript throws an error and does not allow circular dependencies.
- JavaScript allows circular dependencies, and they are resolved at runtime.
- JavaScript handles circular dependencies by allowing them but ensuring that each module loads only once.
- Circular dependencies are not supported in JavaScript.
JavaScript allows circular dependencies, but it ensures that each module is only executed once. This is achieved through a mechanism called "module caching."