| 1 | What is source map support, and why is it important when debugging a transpiled or bundled Node.js application (like TypeScript compiled to JavaScript)? Node.js › Debugging & Diagnostics | Node.js | Debugging & Diagnostics | Intermediate |
| 2 | How do you use the built-in 'debugger' statement together with Node's --inspect flag to set breakpoints in code? Node.js › Debugging & Diagnostics | Node.js | Debugging & Diagnostics | Beginner |
| 3 | How do you use Node's built-in heap snapshot capability to diagnose a suspected memory leak? Node.js › Debugging & Diagnostics | Node.js | Debugging & Diagnostics | Intermediate |
| 4 | What is the DEBUG environment variable convention (popularized by the 'debug' npm package), and how does it let you enable verbose logging selectively? Node.js › Debugging & Diagnostics | Node.js | Debugging & Diagnostics | Intermediate |
| 5 | How would you use the 'clinic.js' toolset (clinic doctor, clinic flame) to diagnose a Node.js performance problem? Node.js › Debugging & Diagnostics | Node.js | Debugging & Diagnostics | Advanced |
| 6 | What is React DevTools and how do you install it? React › React DevTools & Debugging | React | React DevTools & Debugging | Beginner |
| 7 | What is the util module's inspect() function used for, and how does it relate to how console.log() displays objects? Node.js › Core Node.js Modules | Node.js | Core Node.js Modules | Beginner |
| 8 | What is the difference between operational errors and programmer errors in Node.js, and why does this distinction matter? Node.js › Error Handling | Node.js | Error Handling | Beginner |
| 9 | Why is structured (JSON) logging generally preferred over plain-text console.log() statements in a production Node.js application? Node.js › Logging & Monitoring | Node.js | Logging & Monitoring | Beginner |
| 10 | What does the node:util.types module provide, and how does it differ from JavaScript's built-in typeof operator? Node.js › Core Node.js Modules | Node.js | Core Node.js Modules | Intermediate |
| 11 | What is the purpose of setting explicit CPU and memory resource requests and limits for a Node.js container in Kubernetes? Node.js › Docker & Deployment | Node.js | Docker & Deployment | Intermediate |
| 12 | How would you measure how 'busy' the event loop is in a running Node.js process using a simple technique? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Intermediate |
| 13 | What is log level (debug, info, warn, error), and how do you configure a logger like Pino or Winston to filter output by level per environment? Node.js › Logging & Monitoring | Node.js | Logging & Monitoring | Intermediate |
| 14 | What is an APM (Application Performance Monitoring) tool, and what capabilities does it typically add beyond basic logging? Node.js › Logging & Monitoring | Node.js | Logging & Monitoring | Intermediate |
| 15 | How would you generate and interpret a CPU profile for a Node.js application using the built-in --prof flag? Node.js › Performance Optimization & Profiling | Node.js | Performance Optimization & Profiling | Intermediate |
| 16 | How do you use the --inspect flag and Chrome DevTools to profile a running Node.js application in production? Node.js › Advanced Node.js | Node.js | Advanced Node.js | Advanced |
| 17 | What are Node.js's built-in diagnostic reports, and how do you generate one? Node.js › Advanced Node.js | Node.js | Advanced Node.js | Advanced |
| 18 | What is a memory leak in the context of a long-running Node.js server, and what are the most common causes? Node.js › Advanced Node.js | Node.js | Advanced Node.js | Advanced |
| 19 | What is the difference between an unhandled promise rejection and an uncaught exception in Node.js, and how does Node handle each by default? Node.js › Async Patterns | Node.js | Async Patterns | Advanced |
| 20 | What is observability (as distinct from traditional monitoring), and what are its three commonly cited pillars? Node.js › Cloud & DevOps | Node.js | Cloud & DevOps | Advanced |
| 21 | What does the node:perf_hooks module provide, and how would you use it to measure precise execution time of a code block? Node.js › Core Node.js Modules | Node.js | Core Node.js Modules | Advanced |
| 22 | What is error wrapping (or error chaining), and how does the Error class's 'cause' property support it in modern Node.js? Node.js › Error Handling | Node.js | Error Handling | Advanced |
| 23 | What are the distinct phases of the Node.js event loop, and what kind of callbacks does each phase execute? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Advanced |
| 24 | What is 'event loop lag' (or 'event loop delay'), and how would you monitor it in a production Node.js application? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Advanced |
| 25 | How does the V8 JavaScript engine's microtask queue interact with the Node.js event loop's macrotask phases, and why does this occasionally surprise developers? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Advanced |
| 26 | How would you implement conditional middleware in Express that only applies to certain requests based on a runtime condition? Node.js › Express & Middleware | Node.js | Express & Middleware | Advanced |
| 27 | How would you use Git bisect to find the specific commit that introduced a regression in a Node.js application's behavior? Node.js › Git & Project Management | Node.js | Git & Project Management | Advanced |