Type annotations

A type annotation is a colon followed by a type: const width: number = 8; tells TypeScript (and anyone reading the code) that width will always hold a number. Functions work the same way - function area(w: number, h: number): number types each parameter and, after the closing ), the value the function returns.

Annotations don't change what runs - they're erased before your code executes (that's exactly what this playground's TypeScript step does: strip the types, run the plain JavaScript underneath). Their job is to catch mistakes in your editor, and to document what a function expects and hands back.

Your task: finish area(w, h) so it returns w * h, with w, h, and the return value all typed as number.

You'll practice:

Typing a variable with : number
Typing function parameters and a return value

const width: number = 8;
const height: number = 5;

// Write area(w, h): number below - type w, h, and the return value as number.
function area(w: number, h: number): number {

}

const total = area(width, height);