The ______ event of the request object in the http module is emitted when the request body is being received.
- data
- request
- body
The data event of the request object in the http module is emitted when the request body is being received. This event allows you to handle incoming data in chunks, which is particularly useful for processing large request bodies without consuming excessive memory.
You are developing an Express.js application that needs to validate user input on a specific route. How would you implement middleware to efficiently validate input for that route?
- Use the app.use method to add a middleware function to the specific route that performs input validation.
- Include the validation logic directly within the route handler function for the specific route.
- Define a separate middleware function and use app.use to apply it globally for all routes.
- Implement input validation as a part of the route's URL parameters.
To efficiently validate user input for a specific route in Express.js, you should create a dedicated middleware function using app.use and apply it only to the specific route in question. This approach keeps the route handler clean and separates concerns. The other options are less efficient or incorrect approaches.
You are tasked with developing a real-time notification system in Node.js. Which feature of the Events module would be most beneficial in implementing this?
- event.emitOnce()
- event.removeAllListeners()
- event.once()
- event.removeListener()
In a real-time notification system, you would want to ensure that each notification is only sent once to the respective listeners. The event.once() method allows you to do this as it automatically removes the listener after it's been invoked once, ensuring efficient and clean handling of notifications. The other options are useful for managing listeners but do not guarantee a one-time notification.
Which Express.js function is used to create an instance of a router object?
- app.route()
- express.router()
- express.Router()
- app.useRouter()
In Express.js, you create an instance of a router object using express.Router(). Routers are used to modularize routes and middleware. The other options do not create router instances in the standard Express.js way.
How can you handle error events emitted by the request object in the http module?
- request.on('error', (error) => { /* Handle error here */ });
- request.error((error) => { /* Handle error here */ });
- request.catch((error) => { /* Handle error here */ });
- request.onError((error) => { /* Handle error here */ });
To handle error events emitted by the request object in the http module, you can use the request.on('error', (error) => { /* Handle error here */ }); syntax. This allows you to register a callback function to handle errors when they occur during the HTTP request.
What is the primary advantage of using connection pooling when interacting with a database?
- Improved Performance
- Enhanced Security
- Simplified Query Language
- Reduced Data Redundancy
Connection pooling improves performance. It allows reusing established database connections, reducing the overhead of creating and closing connections for every database operation. This results in faster response times and efficient resource usage.
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 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.
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.
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 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.
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.