Part of the Full-Stack TypeScript track · course 1 of 7
JavaScript, Refreshed
A fast, concrete refresher on the JavaScript you actually use: how values and types behave, how functions and closures capture state, and how arrays, objects, and async code really work. Every lesson ends with a runnable challenge that models the concept in plain JavaScript.
5 lessons · ~2 hours
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Values, types & coercion. The rest of the course unlocks with a free account.
1. JavaScript, Refreshed
Values, types & coercion
Every value has a type, and JavaScript will quietly convert types for you unless you stop it.
Functions, scope & closures
Functions are values, and they remember the scope they were born in.
Arrays & objects
Transform data with map, filter, and reduce, and unpack it with destructuring and spread.
Asynchrony: callbacks → promises → async/await
The event loop runs your sync code first, then microtasks, then timers — async/await is sugar over that order.
Modern syntax & immutability
Optional chaining, nullish coalescing, and spread copies let you update state without mutating it.