Error message on key press in app

Ionic Framework Ionic Angular
1

Screenshot_2020-04-15-13-17-33-29
Screenshot_2020-04-15-13-17-33-29720×1520 138 KB

here i need to show error message on click of dash(-) how to do that if i use keycode==45 it is working fine in browser but not in mobile let me know solution i am searching from last one week