
JavaScript Intermediate
Closures, async, and the patterns real apps use.
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Lesson 1 — Destructuring & spread
easy · 8 min
Lesson 2 — Closures & private state
medium · 9 min
Lesson 3 — Promises
medium · 10 min
Lesson 4 — async / await
medium · 10 min
Lesson 5 — Classes
medium · 9 min
Lesson 6 — Merging with spread
medium · 8 min
Lesson 7 — Optional chaining
medium · 8 min
Lesson 8 — Object.entries
medium · 9 min
Lesson 9 — flat & flatMap
medium · 9 min
Lesson 10 — Default & named params
medium · 8 min
Lesson 11 — Nullish & optional deep
medium · 8 min
Lesson 12 — Immutable updates
medium · 9 min
Lesson 13 — reduce
hard · 10 min
Lesson 14 — async functions
hard · 12 min
Lesson 15 — Map & Set
hard · 10 min
Lesson 16 — Promise chaining
hard · 11 min
Lesson 17 — Regular expressions
hard · 11 min
Lesson 18 — Module pattern
hard · 11 min
Lesson 19 — Promise.all
hard · 11 min
Lesson 20 — Generators
hard · 11 min
Lesson 21 — Currying
hard · 11 min
Lesson 22 — Compose & pipe (expert)
hard · 13 min
Lesson 23 — Promisify a callback
very hard · 14 min
Lesson 24 — Concurrency limiter
very hard · 15 min
Lesson 25 — Ultimate: hash router
★ ultimate · 15 min