You are building an Express.js API and need to ensure that the API can only be accessed with a valid authentication token. How would you implement middleware to secure your API?
- Use a middleware function to check the authentication token for each API route and grant access only if the token is valid.
- Implement authentication within each route handler, verifying the token before processing the request.
- Rely on HTTPS encryption to secure the API and avoid using authentication middleware.
- Use a third-party authentication service to secure your API and handle token validation externally.
To secure an Express.js API with authentication, you should create a middleware function that checks the authentication token for each API route and grants access only if the token is valid. Centralizing authentication in middleware ensures consistent security across all routes. The other options are either less secure or less maintainable.
You are working on a large codebase with multiple developers, and you notice inconsistencies in coding styles. How can ESLint help in maintaining a consistent coding style across the project?
- Manually review and correct code style issues.
- Create a shared ESLint configuration and enforce it across the project.
- Ignore coding style issues to avoid conflicts.
- Encourage developers to use their preferred coding styles.
ESLint can help maintain a consistent coding style by creating a shared ESLint configuration that defines the coding style rules. This configuration can be enforced across the project, ensuring that all developers adhere to the same coding standards. Manually reviewing, ignoring issues, or allowing personal preferences would lead to inconsistencies.
You are implementing a Single Sign-On (SSO) solution for various microservices in your organization. How would you design the OAuth flows to ensure secure and seamless access to all services for the end-users?
- Use OAuth 2.0 Authorization Code Flow
- Use OAuth 2.0 Implicit Flow
- Use OAuth 2.0 Resource Owner Password Credentials (ROPC) Flow
- Use OAuth 2.0 Client Credentials Flow
To ensure secure and seamless SSO, the OAuth 2.0 Authorization Code Flow is typically used. It allows the client to securely obtain tokens on behalf of the user without exposing sensitive information. The Implicit Flow is less secure, and ROPC and Client Credentials Flows are not suitable for user authentication.
The package-lock.json file contains a ______ field that represents the exact installed version of each package.
- version
- lock
- dependencies
- resolved
The package-lock.json file contains a resolved field that represents the exact installed version of each package. This field specifies the exact URL that was resolved to fetch a particular package version. It is a crucial part of package management in Node.js.
You are working on a project with tight deadlines, and there is limited time for testing. How would you prioritize testing activities to ensure the quality of the application without compromising the timeline?
- ) Prioritize Functional Testing and skip Performance Testing
- b) Reduce test coverage and focus on critical paths
- c) Extend the project timeline to accommodate comprehensive testing
- d) Skip testing and rely on post-release bug fixes
When facing tight deadlines, it's advisable to reduce test coverage and focus on critical paths (Option b). Skipping testing (Option d) is not a recommended practice as it can lead to significant post-release issues. Extending the timeline (Option c) may not be feasible, and prioritizing Functional Testing while skipping Performance Testing (Option a) can leave performance issues unaddressed.
You are optimizing the performance of a web application that uses EJS for rendering views. The views have a lot of dynamic content and are currently slow to render. How would you approach optimizing the rendering performance of the EJS templates?
- Implement caching mechanisms for frequently accessed templates using a caching library like Redis.
- Minimize the use of JavaScript in templates and offload complex logic to the server-side to reduce client-side rendering time.
- Precompile EJS templates into JavaScript functions to reduce runtime rendering overhead.
- Increase the client-side rendering capabilities by using a JavaScript framework like React or Angular.
To optimize the rendering performance of EJS templates, one effective approach is to precompile EJS templates into JavaScript functions. This reduces the runtime rendering overhead and improves the efficiency of rendering dynamic content.
In JavaScript, a closure is created when an inner function accesses the ________ of an outer function after the outer function has executed.
- parameters
- variables
- methods
- properties
In JavaScript, a closure is created when an inner function accesses the variables of an outer function after the outer function has executed. Closures allow inner functions to "remember" and access the variables of their containing (outer) function even after the outer function has finished executing. This is a fundamental concept for managing scope and data privacy in JavaScript.
You are tasked with developing a real-time chat application where low latency and high availability are critical. Which type of database would be the most suitable, and what considerations should you have in mind regarding data consistency and partitioning?
- Relational Database
- NoSQL Database
- Graph Database
- In-Memory Database
For a real-time chat application, a NoSQL database would be most suitable due to its ability to handle high concurrency and unstructured data. Considerations for data consistency would involve choosing an appropriate consistency model, like eventual consistency, and partitioning data for scalability and low latency.
How does cache eviction strategy LRU (Least Recently Used) work?
- LRU removes the item that was accessed most recently.
- LRU removes the item that was accessed least recently.
- LRU removes the item with the smallest key.
- LRU removes items randomly.
LRU (Least Recently Used) eviction strategy removes the item from the cache that was accessed the least recently. This ensures that the cache retains the most recently accessed items, optimizing for cache hits.
Utilizing closures with caution is essential as they can lead to potential memory leaks due to retained ________.
- Variables
- Functions
- References
- Objects
Closures retain references to their containing scope, which includes variables and functions. If not managed carefully, this can lead to memory leaks as these references may prevent objects from being garbage collected.