Returning a value

Write a function that computes a number and returns it, then store the result in a variable.

Functions can hand a value back

So far our functions have *done* things (drawn shapes). A function can also compute a value and hand it back with the return keyword. The returned value takes the place of the call, so you can store it in a variable.

function double(n) {
  return n * 2;
}

let result = double(21); // result is now 42

double() returns a number you can use.

When the code hits return, the function stops and gives back that value. Here double(21) becomes 42, which we save in result.

Compute an area, then print it.

Return vs. print

println *shows* a value; return *hands it back* so your program can keep using it. They're not the same — a returned value can be added, compared, or passed along.

Functions can hand a value back

Your turn