Intro to TypeScript
Intermediate
About JavaScript →
Type annotations, typed arrays and functions, and your own custom types. 5 quick lessons that build on Intro to JavaScript.
0 / 5 lessons complete
Start Lesson 1
Open the TypeScript sandbox ↗
1
Your First Type
Add a type annotation and see what TypeScript is for.
2
The Built-in Types
Meet the three types you'll use most: string, number, boolean.
3
Typed Arrays
Arrays that only accept one type of item.
4
Functions with Types
Promise what goes into a function, and what comes back out.
5
Custom Types
Invent your own type with its own shape.