What strategies can be employed to optimize aggregation queries in NoSQL databases like MongoDB?
- Aggregation queries in NoSQL databases like MongoDB can be optimized by using the aggregation framework provided by MongoDB, creating proper indexes on fields used in aggregation stages, leveraging server resources efficiently, and using projection to limit the output data size.
- Aggregation queries in NoSQL databases cannot be optimized.
- Aggregation queries in NoSQL databases can only be optimized by using raw database queries with no additional strategies.
- Aggregation queries in NoSQL databases should be avoided altogether.
Aggregation queries in NoSQL databases can be resource-intensive, but they can be optimized using MongoDB's aggregation framework and other techniques to improve query performance.
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 create an object in JavaScript that does not inherit the prototype from Object?
- Object.create(null)
- Object() constructor
- {} constructor
- Object.assign({})
In JavaScript, you can create an object that does not inherit the prototype from Object by using Object.create(null). This creates an object with no prototype, making it a clean slate. The other options either inherit from Object or use Object's prototype.
In Express, how can you enable Cross-Origin Resource Sharing (CORS) for your API?
- app.use(cors())
- app.enable(cors)
- app.allow(CORS)
- app.cors(true)
To enable Cross-Origin Resource Sharing (CORS) in Express, you should use the cors middleware by adding app.use(cors()) to your application. This middleware allows or restricts cross-origin HTTP requests. The other options are not valid ways to enable CORS in Express.
What is the primary purpose of using JSON Web Tokens (JWT) in authentication?
- Storing user passwords securely
- Encoding user data in URL parameters
- Storing user sessions on the server
- Securely transmitting information between parties
The primary purpose of using JSON Web Tokens (JWT) in authentication is to securely transmit information between parties. JWTs are used to authenticate users and ensure that data exchanged between the client and server remains tamper-proof and confidential. They are commonly used in web applications to maintain user sessions without the need to store session data on the server. The other options do not represent the primary purpose of JWTs.
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 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.
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.