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function greeter(person: string) { return "Hello, " + person; } const user = "World"; console.log(greeter(user));
greeter([1,2])
string
number
boolean
This no-setup environment lets you focus on concepts immediately.
❌ Overlooking type inference by always annotating
→Let TypeScript infer types where obvious, annotate only when needed
❌ Ignoring error messages
→Read the hover tooltip for detailed error explanations
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learntypescript.dev
Codecademy
learn-ts.org
by Basarat Ali Syed
by Josh Goldberg
Official guide covering basics to advanced
Online editor for instant experimentation
Source repo with latest releases and contrib
Runtime for running TS-compiled JS
Editor with built-in TS language support
Package manager for installing TypeScript