You are working on a Node.js project with a team, and you notice that the package-lock.json file is frequently causing merge conflicts. How would you resolve or minimize such conflicts while ensuring consistent dependency resolution?
- Remove the package-lock.json file entirely
- Use Yarn instead of npm
- Use a tool like npm ci and enforce it in your team's workflow
- Manually edit the package-lock.json file in case of conflicts
To minimize package-lock.json merge conflicts, you should use a tool like npm ci in your team's workflow. npm ci installs dependencies based on the package-lock.json and ensures consistent dependency resolution. Options 1 and 2 are not recommended, and option 4 is not a practical solution.
What is the difference between chaining multiple .then() methods and using multiple await expressions?
- Chaining .then() is more efficient for error handling
- Chaining .then() is better for readability
- Using multiple await expressions allows better error propagation
- Using multiple await expressions guarantees faster execution
When using await expressions, errors can be propagated using standard try/catch blocks, which allows for more granular and flexible error handling. Chaining multiple .then() methods can lead to less readable and maintainable code when dealing with multiple asynchronous operations. It's not a question of efficiency or speed but rather about readability and error handling.
The prototype of an instance object in JavaScript is found using the ______ property.
- __proto__
- instanceOf
- type
- parent
The __proto__ property is used to access the prototype of an instance object in JavaScript. This is how objects inherit properties and methods from their constructor's prototype.
Express.js middleware functions have access to the ______ object, the ______ object, and a next function in their callback function parameters.
- request, response
- response, request
- req, res
- req, next
In Express.js middleware functions, the callback function parameters typically include req (the request object) and res (the response object). Additionally, you can use a next function to pass control to the next middleware function in the pipeline. This allows you to manipulate the request and response objects or perform actions before sending a response to the client.
You are maintaining a server that has strict security requirements. You need to allow cross-origin requests but with stringent restrictions. How can you implement CORS to fulfill these requirements while maintaining security?
- Set Access-Control-Allow-Origin to * and rely on server-side authentication.
- Implement preflight requests with custom headers and allow only authorized clients.
- Avoid using CORS and handle cross-origin requests through server-side scripting.
- Enable CORS for all origins and use server-side IP filtering.
To implement stringent security with CORS, you should use preflight requests with custom headers to allow only authorized clients. Option A is not secure as it allows any origin. Option C suggests avoiding CORS altogether, which may not be practical. Option D relies on IP filtering, which can be bypassed.
In JavaScript, closures are crucial for functional programming as they facilitate the creation of ________.
- Private Variables
- Callbacks
- Promises
- Modules
Closures in JavaScript allow the creation of private variables within functions. This encapsulation is essential for functional programming, where data should be isolated and not directly accessible from outside the function.
You are developing a high-traffic e-commerce website. You need to implement a caching strategy to ensure that the load on the database is minimized, and the data retrieval is fast. Which caching strategy would be most suitable, and why?
- In-Memory Caching
- File-Based Caching
- Database Indexing
- No Caching
In this high-traffic scenario, In-Memory Caching would be the most suitable caching strategy. It stores frequently accessed data in RAM, ensuring rapid data retrieval and minimizing the load on the database server. File-Based Caching and Database Indexing may not offer the same level of performance improvement, and not using caching (No Caching) would increase the load on the database.
Why is input validation crucial in web development?
- To ensure data is entered correctly.
- To make web forms look more attractive.
- To increase website loading speed.
- To prevent SQL injection.
Input validation is crucial in web development to prevent security vulnerabilities like SQL injection and to ensure that the data entered by users is correct and safe. It helps protect against malicious input and maintain data integrity.
You are tasked with improving the reliability of a large codebase. Using Jest, how would you approach writing tests for functions with side effects like database calls or API requests?
- Use Jest's mocking capabilities to create mocks or spies for database and API calls.
- Skip testing functions with side effects; focus on pure functions.
- Manually perform database/API calls in tests to ensure real-world reliability.
- Use only integration tests for functions with side effects.
To improve reliability and isolate side effects, you should use Jest's mocking capabilities to create mocks or spies for database and API calls. This way, you can control and verify the behavior of these calls without involving the actual database or API. The other options may lead to unreliable tests or skipped testing.
When a package is listed under devDependencies, it means that the package is only required during the ________ of the application.
- development
- deployment
- testing
- runtime
When a package is listed under devDependencies, it means that the package is only required during the development of the application. These are typically tools and libraries used for development, such as testing frameworks, build tools, and linters. They aren't needed in the production or deployment environment.