Disable functionality can also be achieved using ACL's as well (button will not get disabled but delete operation will fail). You can set ACL on content node of page or asset (remove delete privilege) via custom Preprocessor when a page/asset is published. When a page is unpublished, you can remove these ACLs.
it should not show disable mode in every time.it has to show enable mode when page is not in published status.
Below is the status has to show when page is in activated or deactivated status:
if page is activated -disable delete button
if page is not activated - enable delete button
when author selects the page from console it shows action tool bar (these action bar items populates using listeners). so i want the listeners (java script files) that shows for action bar after selecting the page from console.if we know that, we can add our disable condition on listener.