| 1 | What is Express.js, and what problem does it solve compared to using Node.js's raw http module directly? Node.js › Express & Middleware | Node.js | Express & Middleware | Beginner |
| 2 | What is the difference between application-level, router-level, and route-specific middleware in Express? Node.js › Express & Middleware | Node.js | Express & Middleware | Intermediate |
| 3 | What does the express.json() and express.urlencoded() built-in middleware do, and why must it be registered before routes that need to read req.body? Node.js › Express & Middleware | Node.js | Express & Middleware | Intermediate |
| 4 | What is the difference between res.send(), res.json(), and res.end() in Express, and when should each be used? Node.js › Express & Middleware | Node.js | Express & Middleware | Intermediate |
| 5 | How would you set up a basic GraphQL server in Node.js using Apollo Server, and what are schema and resolvers? Node.js › GraphQL with Node.js | Node.js | GraphQL with Node.js | Beginner |
| 6 | What does the URL/URLSearchParams API provide, and why is it generally preferred over the older querystring module today? Node.js › Core Node.js Modules | Node.js | Core Node.js Modules | Beginner |
| 7 | What is GraphQL, and how does it differ from a traditional REST API in terms of how clients request data? Node.js › GraphQL | Node.js | GraphQL | Beginner |
| 8 | How would you create a basic HTTP server in Node.js using only the built-in node:http module, without any framework? Node.js › HTTP & Web Servers | Node.js | HTTP & Web Servers | Beginner |
| 9 | How would you implement a global 'not found' (404) handler in Express for any route that doesn't match a defined endpoint? Node.js › Error Handling | Node.js | Error Handling | Intermediate |
| 10 | What is content negotiation in HTTP, and how would a Node.js API implement it to return either JSON or XML based on a client's Accept header? Node.js › HTTP & Web Servers | Node.js | HTTP & Web Servers | Intermediate |
| 11 | What is a centralized error-handling middleware pattern in Express, and what advantages does it provide over handling errors in each individual route? Node.js › Error Handling | Node.js | Error Handling | Advanced |
| 12 | What is the difference between a 4xx and 5xx HTTP status code from an error-handling perspective, and how should a Node.js API decide which to return? Node.js › Error Handling | Node.js | Error Handling | Advanced |
| 13 | How would you implement error handling for a GraphQL API in Node.js, given GraphQL's different error-response format compared to REST? Node.js › Error Handling | Node.js | Error Handling | Advanced |
| 14 | What is the difference between a GraphQL query variable and hardcoding a value directly inside the query string? Node.js › GraphQL | Node.js | GraphQL | Beginner |
| 15 | What is the difference between an HTTP request header and a query parameter, and when should each be used to pass information to a Node.js server? Node.js › HTTP & Web Servers | Node.js | HTTP & Web Servers | Beginner |
| 16 | How would you create and use custom Error subclasses in a Node.js application to represent different categories of application-specific errors? Node.js › Error Handling | Node.js | Error Handling | Intermediate |
| 17 | What is the difference between a validation error and a business-logic error, and how might a Node.js application handle each differently? Node.js › Error Handling | Node.js | Error Handling | Intermediate |
| 18 | How would you set up a basic GraphQL server in Node.js using Apollo Server, defining a schema and resolvers? Node.js › GraphQL | Node.js | GraphQL | Intermediate |
| 19 | What is the difference between a GraphQL Query, Mutation, and Subscription operation type? Node.js › GraphQL | Node.js | GraphQL | Intermediate |
| 20 | What is GraphQL introspection, and why might you want to disable it in a production environment? Node.js › GraphQL | Node.js | GraphQL | Intermediate |
| 21 | What is the purpose of GraphQL fragments, and how do they help avoid duplicating field selections across multiple queries? Node.js › GraphQL | Node.js | GraphQL | Intermediate |
| 22 | What is the purpose of GraphQL's non-null (!) type modifier, and what happens if a resolver for a non-null field returns null unexpectedly? Node.js › GraphQL | Node.js | GraphQL | Intermediate |
| 23 | What is the difference between a GraphQL scalar type and an object type, and how would you define a custom scalar (like DateTime) in a Node.js GraphQL server? Node.js › GraphQL | Node.js | GraphQL | Intermediate |
| 24 | What is the difference between HTTP methods GET, POST, PUT, PATCH, and DELETE, and what does 'idempotent' mean in this context? Node.js › HTTP & Web Servers | Node.js | HTTP & Web Servers | Intermediate |
| 25 | What is the difference between a 301 and a 302 HTTP redirect, and when should a Node.js application use each? Node.js › HTTP & Web Servers | Node.js | HTTP & Web Servers | Intermediate |