You are designing a real-time data processing system where data needs to be transformed before being sent to another service. How would you implement streams in Node.js to ensure smooth data transformation and transmission?
- Use a single function to transform data and send it directly to the service.
- Implement a Readable stream to receive data, transform it with a Transform stream, and then pipe it to a Writable stream that sends it to the service.
- Store all incoming data in memory, transform it, and then send it to the service.
- Use asynchronous callbacks to process data and send it to the service as it arrives.
In a real-time data processing system, you should implement streams. Use a Readable stream to receive data, transform it with a Transform stream, and then pipe it to a Writable stream that sends it to the service. This approach allows for smooth data transformation and transmission without storing large amounts of data in memory.
What could be a potential issue if the prepublish script is used in the package.json file?
- It may slow down the installation process
- It can result in circular dependencies
- It may conflict with the postpublish script
- There are no issues with using prepublish
Using the prepublish script in package.json can potentially lead to circular dependencies in your Node.js application. This is because the script runs before the package is published, and if it modifies files that are required for the package to work, it can cause problems.
When using dynamic imports, the import() function returns a ________.
- Promise
- Callback
- Function
- Object
When using dynamic imports in JavaScript, the import() function returns a Promise. This Promise resolves to the module's namespace object once the module is loaded and ready for use.
What is the primary purpose of the package-lock.json file in a Node.js project?
- To store documentation for the project
- To store a backup of the package.json file
- To specify the version of Node.js to use
- To lock the version of each package's dependencies
The primary purpose of the package-lock.json file in a Node.js project is to lock the version of each package's dependencies. This ensures that every developer working on the project uses the same versions of dependencies, preventing version conflicts and ensuring consistency across environments. The other options (To store documentation for the project, To store a backup of the package.json file, and To specify the version of Node.js to use) do not accurately describe the purpose of the package-lock.json file.
What is the primary purpose of performance optimization in a Node.js application?
- To reduce memory usage
- To improve code readability
- To increase the number of dependencies
- To enhance application speed
The primary purpose of performance optimization in a Node.js application is to enhance application speed. While other factors like memory usage and code readability are important, the primary goal is to make the application run faster and respond more efficiently to user requests.
The async keyword is used before a function to make it return a ________.
- Promise
- Callback
- Generator
- Function
The async keyword is used before a function to make it return a Promise. It allows you to work with asynchronous code in a more synchronous-like fashion by enabling the use of await within the function.
What is the role of the error-handling middleware when dealing with unhandled promise rejections in Express?
- It converts promise rejections into synchronous errors
- It terminates the Node.js process to prevent unhandled rejections
- It logs the unhandled promise rejection and continues execution
- It captures unhandled promise rejections and sends them to the default error handler
The error-handling middleware in Express captures unhandled promise rejections and sends them to the default error handler. This allows you to handle unhandled promise rejections gracefully in your Express application. The other options are not the typical roles of error-handling middleware in this context.
You are developing a user management system and need to design routes for CRUD operations. How would you structure the routes to follow RESTful principles in Express.js?
- Use any route structure that suits your needs
- Design routes like /createUser, /getUser, /updateUser, /deleteUser
- Structure routes as /users, using HTTP methods (GET, POST, PUT, DELETE) to indicate CRUD operations
- Create routes like /addUser, /fetchUser, /modifyUser, /removeUser
To follow RESTful principles in Express.js, you should structure routes as a resource, such as /users, and use HTTP methods (GET, POST, PUT, DELETE) to indicate CRUD operations on that resource. This approach aligns with RESTful conventions, making your API more intuitive and standardized. Option 2 doesn't follow RESTful principles, and Options 1 and 4 lack the structured approach recommended for RESTful APIs.
To parse URL-encoded data, Express uses the ______ middleware.
- body-parser
- express-parser
- data-parser
- url-parser
Express uses the body-parser middleware to parse URL-encoded data in incoming requests. This middleware is essential for handling form submissions and other data sent in the request body.
How do you correctly implement a middleware function in Express.js?
- Define a function with the signature (req, res)
- Use the middleware() keyword before a route definition
- Import the express-middleware module
- Add a next() function to the route handler
To correctly implement a middleware function in Express.js, you define a function with the signature (req, res). This function can also take an optional next parameter if you want to pass control to the next middleware in the stack. The (req, res) signature allows you to access and modify the request and response objects.