You are implementing error handling in an Express application, and you notice that asynchronous errors are not being caught by your error-handling middleware. How should you modify your error-handling approach to ensure that asynchronous errors are caught?
- Wrap asynchronous code with try-catch blocks
- Use the next function with async/await middleware
- Disable asynchronous error handling
- Increase the Node.js event loop size
In Express.js, asynchronous errors are not automatically caught by synchronous error-handling middleware. To catch asynchronous errors, you should use the next function with async/await middleware to ensure that errors occurring in asynchronous code are properly handled by your error-handling middleware. Wrapping asynchronous code with try-catch blocks won't work for middleware functions.
JavaScript’s ______ operator can be used to create a new object with the specified prototype object and properties.
- New
- Prototype
- Object.create()
- Construct
JavaScript's "Object.create()" operator can be used to create a new object with the specified prototype object and properties. This method is commonly used for creating objects with specific prototypes in JavaScript, allowing for more control over inheritance and object composition.
In Express.js, how does the order in which routes are defined affect the routing mechanism?
- Routes are matched in a random order
- Routes are matched in the order they are defined
- Routes are matched in reverse order
- Routes are matched based on alphabetical order
In Express.js, the order in which routes are defined affects the routing mechanism. Routes are matched in the order they are defined, and the first matching route is executed. This means that the order of route definitions is crucial as it determines which route will handle a request.
What is the primary purpose of implementing CORS in web development?
- Allow cross-origin requests
- Improve website performance
- Enhance security
- Prevent JavaScript errors
The primary purpose of implementing CORS (Cross-Origin Resource Sharing) in web development is to allow cross-origin requests. CORS is a security feature that permits or restricts web pages in one domain from making requests to a different domain, enhancing security by preventing unauthorized access to resources while enabling legitimate cross-origin communication.
What does the 'major' number in a semantic versioning format (e.g. 1.2.3) typically represent?
- Major changes
- Minor changes
- Patch changes
- Build number
In semantic versioning (SemVer), the 'major' number represents significant changes that are not backwards-compatible. This means that if the 'major' version number increases, it indicates that there have been substantial changes in the software that may break compatibility with previous versions.
You are tasked with ensuring that a web application works seamlessly and that all components interact as expected. Which testing approach would be most suitable to verify the interactions between different components and services?
- Unit Testing
- Integration Testing
- Functional Testing
- Usability Testing
To verify interactions between different components and services in a web application, Integration Testing is the most suitable approach. Unit Testing focuses on individual units of code, Functional Testing checks if the application meets its specifications, and Usability Testing focuses on user experience. Integration Testing is specifically designed to test the interactions between components.
What is the result of using the spread operator on a string, such as ...“JavaScript”?
- ["J", "a", "v", "a", "S", "c", "r", "i", "p", "t"]
- "JavaScript"
- SyntaxError
- undefined
When you use the spread operator on a string in JavaScript, it splits the string into an array of individual characters. So, the correct result is an array of characters as shown in Option 1. The other options are not the expected outcome for the spread operator on a string.
In Jest, what is the purpose of the 'expect' function?
- Making Assertions
- Generating Random Data
- Fetching Data from APIs
- Creating Mock Components
In Jest, the 'expect' function is primarily used for making assertions in your test cases. It allows you to check whether the actual value matches the expected value. Assertions are crucial in determining whether your code behaves as intended and whether it passes the test.
What is the primary purpose of using modules in JavaScript?
- Code organization and encapsulation
- Enhancing performance
- Creating user interfaces
- Managing database connections
The primary purpose of using modules in JavaScript is code organization and encapsulation. Modules help break down large programs into smaller, manageable pieces of code, making it easier to maintain and collaborate on projects. While modules can have other benefits, such as enhancing performance, their main role is to structure and organize code.
How can you prevent a specific package from being updated when running npm update?
- Use the "npm lock" command to lock the package's version.
- Edit the package.json file to specify the exact version of the package you want.
- Run "npm update --no-save"
- Delete the package and reinstall it.
To prevent a specific package from being updated when running npm update, you can edit your project's package.json file and specify the exact version of the package you want. This ensures that the package remains at the specified version. Using "npm lock" is not a standard command, and running npm update --no-save will update the package.json file if used. Deleting and reinstalling the package is not a recommended approach as it can disrupt your project.