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18 lessons

JavaScript, finally explained without 47 frameworks

Eight lessons. From "what is var even" to "how the async stuff actually works under the hood." No Webpack, no Vite, no opinions on Redux. Just the language.

Senior path10 lessons

Deep dive for interview prep. Mental models, traps, execution flow.

  1. 09

    Execution context, the call stack, and the hoisting trap

    How JS thinks at runtime, the two passes that explain hoisting, and the classic var trap.

    6 min read
  2. 10

    Scope, lexical environment, and closures (the deep version)

    The chai-stall cash-box analogy that makes closures finally click, plus the for-var-setTimeout trap.

    7 min read
  3. 11

    this, call/apply/bind, and the arrow-function trap

    The four binding rules in one mental model, and why arrow functions are NOT shorter functions.

    7 min read
  4. 12

    The event loop, microtasks vs macrotasks, and the famous output trap

    Why Promise.then runs before setTimeout(fn, 0), explained step by step.

    7 min read
  5. 13

    Promises, async/await, and the order-of-output trap

    Why the rest of an async function is a microtask, and other questions you will be asked.

    7 min read
  6. 14

    Prototype, the prototype chain, and what new actually does

    No class system. Just objects pointing to other objects. Class syntax is sugar.

    7 min read
  7. 15

    Deep vs shallow copy, immutability, and the spread trap

    Why {...obj} is not a deep copy, when JSON.parse is enough, and when to reach for structuredClone.

    7 min read
  8. 16

    Array internals, the methods you actually use, and writing your own

    Sparse vs dense, mutating vs not, and the polyfills every senior is expected to write on a whiteboard.

    8 min read
  9. 17

    Debounce, throttle, memoization, and avoiding memory leaks

    Four classic patterns plus the four memory leaks that silently kill your app.

    8 min read
  10. 18

    Coding interview patterns: Promise.all, deep clone, curry, EventEmitter

    The "implement X from scratch" round, in working code. Plus security and design patterns in one paragraph each.

    9 min read