The JavaScript Language

Scope, closures, asynchrony and modules — the parts interviews actually probe.

7 concepts · 285 minutes

• JavaScript FundamentalsTypes, scope, coercion, `this` — the base layer everything else in this track sits on.
• Callbacks & PromisesHow JavaScript represents 'not yet' — and why a Promise is not a thread.
• async / awaitPromises that read like ordinary code — plus the parallelism people accidentally throw away.
• ES Modulesimport/export, and the CommonJS interop mess you will absolutely hit in Node.
• The Node.js RuntimeJavaScript outside the browser: modules, streams, and a single thread doing a lot of I/O.
• ClosuresFunctions remember where they were born — the mechanism behind hooks, modules, and half of interview questions.
• The Event LoopOne thread, a queue, and a rule about when it drains — the model that explains every 'why did this run last?'.