How can you handle CORS to allow cookies to be included in requests?
- Access-Control-Allow-Origin: *
- Access-Control-Allow-Credentials: true
- Access-Control-Allow-Headers: *
- Access-Control-Allow-Methods: GET, POST
To allow cookies to be included in CORS requests, you should set the Access-Control-Allow-Credentials header to true. The other options are related to different aspects of CORS, but they don't specifically enable cookie handling.
What is the primary use of the spread operator in JavaScript?
- To merge arrays and objects
- To create a new array with the same elements
- To create a deep copy of an object
- To remove elements from an array
The primary use of the spread operator (...) in JavaScript is to merge arrays and objects. It can also be used to clone an array or object, effectively creating a new array or object with the same elements or properties.
How can you handle error responses in Express for cleaner error reporting?
- Using the throw statement
- Using the try...catch block
- Implementing custom error handling middleware
- Ignoring errors for cleaner logs
To handle error responses in Express for cleaner error reporting, you can implement custom error handling middleware. This middleware can catch errors and provide a standardized way to handle and respond to them, improving error reporting and debugging.
In Node.js, a buffer can be converted to JSON using the ______ method.
- toJSON
- bufferToJSON
- JSON.stringify
- serialize
To convert a buffer to JSON in Node.js, you can use the JSON.stringify method. This method will create a JSON string representation of the buffer's contents.
How can you ensure the reliability of your tests in a scenario where external services have inconsistent behavior?
- Mock the external services to simulate consistent behavior; Use retry mechanisms in your tests to account for inconsistencies; Write tests that ignore external services.
- Rely on external services' behavior as is, without any mitigation; Run the tests at a specific time when external services are expected to be consistent; Ignore testing external services.
- Always use real external services in your tests to ensure accuracy; Write tests that fail gracefully when external services are inconsistent; Run tests with random intervals to catch inconsistencies.
- Use external services only for integration tests, not unit tests; Write tests that expect failures due to external services; Use only internal services to avoid inconsistencies.
To ensure test reliability when external services have inconsistent behavior, it's best to mock the external services to simulate consistent behavior during tests. The other options either ignore the issue or rely on unpredictable external behavior.
The process.env object in Node.js contains the ________ variables of the environment where the Node.js process is executed.
- environment
- system
- user
- configuration
The process.env object in Node.js contains the environment variables of the system where the Node.js process is executed. These variables can be used to configure the behavior of the Node.js application based on the environment.
How does the placement of a package in dependencies or devDependencies affect the build process of a project?
- It has no impact on the build process; it's only for organizational purposes.
- Packages in dependencies are bundled together, while devDependencies are loaded asynchronously.
- Dependencies are loaded first and are critical for the build, while devDependencies are optional.
- Packages in devDependencies are included in the production build.
The placement of a package in dependencies or devDependencies affects the build process. Packages in dependencies are critical for the build and are loaded first, while packages in devDependencies are optional and excluded from the production build.
Which of the following is used to consume a Promise?
- then()
- catch()
- finally()
- consume()
To consume the result of a Promise, you typically use the then() method. It allows you to specify what should happen when the Promise is successfully resolved. The other options are also Promise methods but serve different purposes, like error handling with catch() or running code regardless of the Promise's outcome with finally().
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.