JavaScript Array forEach function not working? – Blancer.com Tutorials and projects

I tried to do some changes in the W33 school’s javascript code to learn about the difference
between forEach and map, is there anyone can please tell me why the output of this code is still:

45,4,9,16,25

instead of

90,8,18,32,50

Isn’t it forEach means call a function to every element in this array? I know I should not use return because the forEach does not return valid result.

const numbers = [45, 4, 9, 16, 25];

numbers.forEach(myFunction);
document.getElementById("demo").innerHTML = numbers;

function myFunction(value, index, array) {
  value * 2;
}

<!DOCTYPE html>
<html>

<body>

  <h2>JavaScript Array.forEach()</h2>
  <p>Calls a function once for each array element.</p>

  <p id="demo"></p>

</body>

</html>