1. #1

   Mid-levelclosurespatterns

   How do closures enable data privacy and the module pattern?

   Variables captured in a closure are inaccessible from outside; exposing only selected functions creates private state and a public API.

2. #2

   Seniorevent-loopasync

   Walk through how the event loop orders sync code, microtasks, and timers.

   Synchronous code runs first; then all microtasks drain; then one macrotask runs, after which microtasks drain again — repeating each loop tick.

3. #3

   Seniorprototypesinternals

   How does property lookup traverse the prototype chain?

   Lookup checks the object’s own properties, then follows [[Prototype]] links upward until found or it reaches null, returning undefined if absent.

4. #4

   Seniorthiscontext

   What are the precedence rules for resolving "this"?

   Precedence: new binding, then explicit bind/call/apply, then implicit (object before the dot), then default (undefined in strict mode); arrows inherit lexically.

5. #5

   Seniormemorygc

   How does garbage collection work in JavaScript?

   Modern engines use mark-and-sweep: starting from roots, they mark reachable objects and reclaim everything unmarked, with generational and incremental optimisations.

6. #6

   Seniorasynciterators

   What are async iterators and for-await-of?

   Async iterators yield promises of values; for-await-of consumes them sequentially, ideal for streams and paginated data that arrive over time.

7. #7

   Seniorbinaryperformance

   What are ArrayBuffer and typed arrays used for?

   ArrayBuffer is raw binary memory; typed arrays (Uint8Array, Float32Array) are views over it for efficient handling of binary data, files, and streams.

8. #8

   Seniorstringsmetaprogramming

   How do tagged template literals work?

   A tag function receives the static string parts as an array and the interpolated values as arguments, letting it transform or sanitise the output.

9. #9

   Seniorfunctionalcomposition

   What is function composition and how do pipe/compose work?

   Composition combines small functions into one; compose applies right-to-left and pipe left-to-right, passing each result into the next function.

10. #10

    Seniorasynccancellation

    How do you cancel asynchronous operations with AbortController?

    An AbortController exposes a signal you pass to fetch or listeners; calling abort() rejects the operation and triggers cleanup, preventing races and leaks.