Node.js + Express + REST + GraphQL Interview Examples

This project contains runnable examples for the interview questions in the supplied markdown notes. Each question is placed in a separate file under examples/.

Setup

npm install

Run examples

Run one example at a time because most Express examples use port 3000 and most GraphQL examples use port 4000.

npm run q1
npm run q2
npm run q45

For auto-restart while editing:

npm run dev:q1

Postman collection

Import this file in Postman:

postman/node_express_graphql_questions_no_secrets.postman_collection.json Collection variables to set after import:

baseUrl = http://localhost:3000
graphqlUrl = http://localhost:4000
staticToken = secret123
invalidToken = wrongtoken
jwtToken = paste JWT returned from login examples

The collection avoids hard-coded tokens by using variables like {{staticToken}} and {{jwtToken}}.

Files

Question	File	Topic
1	examples/01-create-a-basic-express-server.js	Create a Basic Express Server
2	examples/02-create-a-custom-logger-middleware.js	Create a Custom Logger Middleware
3	examples/03-create-json-body-parsing-middleware.js	Create JSON Body Parsing Middleware
4	examples/04-create-authentication-middleware.js	Create Authentication Middleware
5	examples/05-attach-user-data-in-middleware.js	Attach User Data in Middleware
6	examples/06-role-based-authorization-middleware.js	Role-Based Authorization Middleware
7	examples/07-global-error-handling-middleware.js	Global Error Handling Middleware
8	examples/08-async-error-handling-wrapper.js	Async Error Handling Wrapper
9	examples/09-create-rest-api-crud-without-database.js	Create REST API CRUD Without Database
10	examples/10-validate-request-body-without-library.js	Validate Request Body Without Library
11	examples/11-validate-request-body-using-zod.js	Validate Request Body Using Zod
12	examples/12-pagination-in-rest-api.js	Pagination in REST API
13	examples/13-search-and-filter-rest-api.js	Search and Filter REST API
14	examples/14-sorting-rest-api-data.js	Sorting REST API Data
15	examples/15-jwt-login-api.js	JWT Login API
16	examples/16-jwt-protected-api-middleware.js	JWT Protected API Middleware
17	examples/17-rate-limiting-middleware.js	Rate Limiting Middleware
18	examples/18-cors-middleware-manually.js	CORS Middleware Manually
19	examples/19-request-id-middleware.js	Request ID Middleware
20	examples/20-api-versioning.js	API Versioning
21	examples/21-express-router-based-structure.js	Express Router-Based Structure
22	examples/22-upload-file-api-using-multer.js	Upload File API Using Multer
23	examples/23-download-file-api.js	Download File API
24	examples/24-read-file-using-node-js.js	Read File Using Node.js
25	examples/25-stream-large-file-in-api.js	Stream Large File in API
26	examples/26-create-graphql-server-with-apollo.js	Create GraphQL Server with Apollo
27	examples/27-graphql-query-for-users.js	GraphQL Query for Users
28	examples/28-graphql-mutation-to-create-user.js	GraphQL Mutation to Create User
29	examples/29-graphql-update-mutation.js	GraphQL Update Mutation
30	examples/30-graphql-delete-mutation.js	GraphQL Delete Mutation
31	examples/31-nested-graphql-resolver.js	Nested GraphQL Resolver
32	examples/32-graphql-pagination.js	GraphQL Pagination
33	examples/33-graphql-authentication-using-context.js	GraphQL Authentication Using Context
34	examples/34-rest-vs-graphql-coding-comparison.js	REST vs GraphQL Coding Comparison
35	examples/35-prevent-n-1-problem-in-graphql.js	Prevent N+1 Problem in GraphQL
36	examples/36-build-a-small-rest-api-with-controller-pattern.js	Build a Small REST API With Controller Pattern
37	examples/37-build-middleware-chain.js	Build Middleware Chain
38	examples/38-middleware-that-stops-request-flow.js	Middleware That Stops Request Flow
39	examples/39-handle-404-route.js	Handle 404 Route
40	examples/40-full-mini-project-rest-api-middleware.js	Full Mini Project: REST API + Middleware
41	examples/41-full-mini-project-graphql-user-api.js	Full Mini Project: GraphQL User API
42	examples/42-node-js-promise-based-api-handler.js	Node.js Promise-Based API Handler
43	examples/43-timeout-middleware.js	Timeout Middleware
44	examples/44-build-api-response-wrapper.js	Build API Response Wrapper
45	examples/45-interview-level-combined-question.js	Interview-Level Combined Question

Notes

• For JWT examples, first call the login request, copy the returned token, and set jwtToken in Postman.
• For upload example 22, use form-data with field name file.
• For download and stream examples, placeholder files are included in data/ and copied into examples/ for convenience.
• These examples are for learning/interview practice. Do not use hard-coded secrets in production.