You are responsible for the security of a web application. You have to ensure that only trusted domains can interact with your server. How would you configure CORS to allow only specific domains to make requests to your server?
- Set the Access-Control-Allow-Origin header to * in the server response.
- Use wildcard subdomains in the Access-Control-Allow-Origin header.
- Specify the trusted domains in the Access-Control-Allow-Origin header.
- Disable CORS entirely to prevent any external access.
To restrict CORS to specific domains, you should specify the trusted domains in the Access-Control-Allow-Origin header. Option A would allow any domain, option B uses wildcard subdomains, which may not be secure, and option D is not secure and disables CORS.
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.
What is the primary purpose of setting up test suites in a testing framework?
- Test suites organize individual test cases into logical groups.
- Test suites improve the performance of test execution.
- Test suites make it easier to write complex test cases.
- Test suites ensure that tests are executed in random order.
Test suites in a testing framework are used to organize individual test cases into logical groups, making it easier to manage and execute tests. This helps maintain a structured and organized testing process.
You are tasked with optimizing a Node.js application suffering from frequent delays and unresponsive behavior. How would you diagnose and address potential issues related to the Event Loop and blocking operations?
- Increase the size of the Event Loop thread pool.
- Use profiling tools like Node.js built-in profiler or third-party tools like Clinic.js.
- Replace Node.js with a different runtime environment.
- Use synchronous file I/O operations for better performance.
To diagnose and address issues related to the Event Loop and blocking operations in Node.js, you should use profiling tools like Node.js built-in profiler or third-party tools like Clinic.js. These tools help you identify bottlenecks and performance issues in your code. Options a, c, and d are not recommended solutions and may lead to further issues.
In the context of testing, what is the main difference between a mock and a stub?
- Stubs are used for functions, while mocks are used for objects
- Mocks record and verify interactions, while stubs only simulate behavior
- Stubs are only used in integration tests, while mocks are used in unit tests
- Mocks are less flexible than stubs
The primary difference between a mock and a stub is that mocks record and verify interactions between the code under test and the dependencies, whereas stubs only simulate the behavior of dependencies. Mocks are used to ensure that specific interactions occur as expected, while stubs focus on controlling the response of functions or methods.
In Express.js, how can middleware be utilized to implement authorization checks for different routes?
- Middleware can't be used for authorization checks in Express.js.
- Middleware functions can be added to route definitions to execute specific authorization logic before handling a request.
- Middleware can only be used for logging purposes in Express.js.
- Authorization checks can only be done in the route handler functions.
Middleware in Express.js is versatile and can be used for various purposes, including implementing authorization checks. By adding middleware functions to specific route definitions, you can ensure that certain authorization logic is executed before the route handler processes the request.