Request Approval UI Action on change form

Hi,

I have a requirement where I need to display a confirm message when a user clicks on request approval UI Action.

The form should remain on the same page when user clicks CANCEL.

I've written a onSubmit Client Script.

This is the UI Action.

Issue is the form is moving to assess even after selecting CANCEL. Can anyone figure out what the exact issue is and suggest appropriate changes.

Thanks

Aditya