Is there a software for creating macros that can work with selected text?

Question

JavaScript

I'm looking for a program that, by pressing some buttons or combinations, can somehow process the selected text. And so that you can write the handler yourself, ideally in JS.

Example:
1) I select the word "toaster"
2) I press some button
3) the program receives the selected word and passes it to my handler

const textEdit = (str) => {
  if(str) str[0] = str[0].toUpperCase();
  return str;
};

4) the program enters "Toaster" replacing the previously highlighted word.

Answer 1

so you can write all this yourself in JS, without using any software

Answer 2

hotkey master
macro recorder