How to use only Digits ,Backspace ,Delete button only in PDF using JavaScript

[Sibi MG]

Ho to modify the following code just to add backspace and delete button to the allowed list.

var digits = /^\d$/;

if(event.willCommit == false){

  if(event.change && digits.test(event.change) == false){

          app.beep();

          event.rc = false;

         }

}

[Bernd Alheit]

What is the issue with this script?

[ls_rbls]

You may need to elaborate your question, it's a little difficult to understand the exact workflow that you're trying to achieve.

For example, are you asking to fornat a text field to display only numerical characters (no letters or special characters)?

And Are you also asking if you can add a button object to the PDF so that when a user clicks  on it it will delete the numeric strings entered in that field  in the same way like a backspace key would do when it is pressed repeatedly on an actual keyboard peripheral device?