Creating an undo/redo store

Typically, we change a store’s value using the set method. However, the next custom Svelte store we’ll explore provides additional custom methods to update its store value. The next custom Svelte store that we are going to look at is an undo/redo store. It is similar to a writable store where you can subscribe to and set a new store value. But an undo/redo store also comes with two more methods, undo and redo, which revert the store value backward or forward, based on the history of the store value.

Here’s a snippet of how you would use an undo/redo store:

<script>
  let value = createUndoRedoStore();
  $value = 123;
  $value = 456;
  $value = 789;
  value.undo(); // $value now goes back to 456
  value.undo(); // $value now goes back to 123
  value.redo(); // $value now turns to 456
</script>
Value: {$value}

In the provided code snippet, the createUndoRedoStore...