Replacing example

https://stackoverflow.com/questions/72115552/how-can-i-repair-my-html-code-to-convert-letters-to-numbers

by Sasha Rudan

HTML

<!DOCTYPE html>
<html>
  <head>
    <script>
      function replace(){
        var text = document.getElementById("textarea").value;
        text = text.replace("a", "11");
        text = text.replace("b", "12");
        text = text.replace("c", "13");
        document.getElementById("textarea").value = text;
      }
    </script>
  </head>
  <body>
    <textarea rows="4" cols="50" id="textarea"></textarea>
    <button id="button" onclick="replace();">replace</button>
  </body>
</html>