0. Go to https://RTCode.io/x/
1. Type a number
2. Select the number
3. Press ↑/↓ keys
3. Open the context menu (right click/long tap)
4. Mess with Selections: or Eval menu items
Claude has helped with the selection actions!
See https://diff.rt.ht which is also built on Monaco!
For more advanced stuff visit: https://go.rt.ht and select the Backend or PDF starters and hover over the attributes!
Feel free to view the sources to see how I script it!