How to override Edit button to show custom popup in Jira Cloud?

[Hung Quoc]

Hello everyone, 

Is it possible to override to show custom popup when user hit on Edit button? as well as Delete button? 

[Nic Brough -Adaptavist-]

Only by amending the core code in Jira (which will leave you unsupported and make upgrades a lot harder)

These buttons do one thing, and they do it well.  Could you explain why you want to change what they do?  We might be able to give you alternatives to "hack the core code" if we know what you are trying to achieve.