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typescript · level 1 · unit 7 · lesson 3

  1. meet it
  2. guess first
  3. your turn
  4. fix it
  5. nailed it

Tap a green word if you get lost.

meet it

hands the answer back so you can keep it.

So far your functions show things. Showing puts a value on the screen, and then it is gone. Your program cannot catch it, keep it or do maths with it.

To return a value, write return and the value. The call then turns into the answer, as if double(4) were the number 8. Add a after the brackets, like : number.

A function that hands nothing back has the return type , which means empty. Catch its answer anyway and you get undefined.

function double(n: number): number {
  return n * 2;
}
let answer: number = double(4);
console.log(answer);
console.log(double(answer));

Showing is telling someone your answer, and return is handing it to them.