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.
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.
What is the main difference between SQL and NoSQL databases regarding data structure?
- SQL databases are faster than NoSQL databases.
- SQL databases are faster than NoSQL databases.
- SQL databases are limited to relational data, while NoSQL databases can handle any data type.
- SQL databases are open source, while NoSQL databases are proprietary.
The main difference is that SQL databases use a structured, tabular format for data storage, adhering to a fixed schema, while NoSQL databases use various flexible data models, making them suitable for unstructured or semi-structured data. SQL databases are not inherently faster, and the choice depends on the specific use case.
How can you match routes with a specific pattern in Express.js?
- app.pattern('/route', callback)
- app.match('/route', callback)
- app.use('/route', callback)
- app.get('/route', callback)
In Express.js, you can use the app.get('/route', callback) method to match routes with a specific pattern. The get method is used to handle HTTP GET requests and is often used to define routes with specific patterns. The other options do not represent the standard way to define route patterns in Express.js.
You are tasked with iterating over an array and modifying each element. Which loop structure would be the most suitable, considering the modern ECMAScript standards and why?
- for loop
- while loop
- for...in loop
- for...of loop
In modern ECMAScript standards, the for...of loop is the most suitable for iterating over an array and modifying each element. It provides a cleaner syntax and avoids issues with unexpected behavior that can occur with the for...in loop when working with arrays. The for loop and while loop are also options, but the for...of loop is more concise and specifically designed for array iteration.