| 1 | What is CORS and why does the browser block certain cross-origin requests? JavaScript › Networking: Fetch, XHR, WebSockets & CORS | JavaScript | Networking: Fetch, XHR, WebSockets & CORS | Intermediate |
| 2 | What is a CORS preflight request, and which requests trigger one? JavaScript › Networking: Fetch, XHR, WebSockets & CORS | JavaScript | Networking: Fetch, XHR, WebSockets & CORS | Advanced |
| 3 | How do Server-Sent Events (SSE) differ from WebSockets, and when would you choose them? JavaScript › Networking: Fetch, XHR, WebSockets & CORS | JavaScript | Networking: Fetch, XHR, WebSockets & CORS | Advanced |
| 4 | How do you make a basic GET request with fetch()? JavaScript › Networking: Fetch, XHR, WebSockets & CORS | JavaScript | Networking: Fetch, XHR, WebSockets & CORS | Beginner |
| 5 | How do you send a POST request with a JSON body using fetch()? JavaScript › Networking: Fetch, XHR, WebSockets & CORS | JavaScript | Networking: Fetch, XHR, WebSockets & CORS | Beginner |
| 6 | Why does fetch() NOT reject its Promise for HTTP error responses like 404 or 500? JavaScript › Networking: Fetch, XHR, WebSockets & CORS | JavaScript | Networking: Fetch, XHR, WebSockets & CORS | Intermediate |
| 7 | How do you cancel an in-flight fetch() request? JavaScript › Networking: Fetch, XHR, WebSockets & CORS | JavaScript | Networking: Fetch, XHR, WebSockets & CORS | Intermediate |
| 8 | What is XMLHttpRequest and why would you still use it over fetch() today? JavaScript › Networking: Fetch, XHR, WebSockets & CORS | JavaScript | Networking: Fetch, XHR, WebSockets & CORS | Advanced |
| 9 | How does a WebSocket connection differ fundamentally from repeated fetch() requests? JavaScript › Networking: Fetch, XHR, WebSockets & CORS | JavaScript | Networking: Fetch, XHR, WebSockets & CORS | Advanced |
| 10 | How would you implement request retries with exponential backoff and a total timeout using fetch()? JavaScript › Networking: Fetch, XHR, WebSockets & CORS | JavaScript | Networking: Fetch, XHR, WebSockets & CORS | Advanced |
| 11 | What does event.preventDefault() do? JavaScript › DOM & Events | JavaScript | DOM & Events | Beginner |
| 12 | How do you convert a JavaScript object into a JSON string? JavaScript › JSON & Data Serialization | JavaScript | JSON & Data Serialization | Beginner |
| 13 | What is a DataView and when would you use it over a TypedArray? JavaScript › ArrayBuffer, TypedArrays & Binary Data | JavaScript | ArrayBuffer, TypedArrays & Binary Data | Intermediate |
| 14 | What is the ReadableStream API used for? JavaScript › Async Iterators & Streams | JavaScript | Async Iterators & Streams | Intermediate |
| 15 | What's the difference between piping streams with pipeThrough() and pipeTo()? JavaScript › Async Iterators & Streams | JavaScript | Async Iterators & Streams | Advanced |
| 16 | How does the Geolocation API work and what are its privacy implications? JavaScript › Browser Storage & Web APIs | JavaScript | Browser Storage & Web APIs | Advanced |
| 17 | What is the Error cause option and what problem does it solve? JavaScript › Error Handling | JavaScript | Error Handling | Advanced |