Adding javascript code into user actions assign task operation

Question

Hi all,
     I've a severe issue , i searched for a solution and nothing returned till my mind blown , i made a process and put a lot of assign task operations with user actions {"Approve","Reject"} what i want to do is when the user hits Reject action a pop-up window is opening to him to put his rejection reasons / justifications, till now i couldn't find a solution or an article writing about a solution for it, so your help is urgently required.
Thanks in advance & have a nice day.

Answer 1

Hi,                                                             
It will not easy to add actions to an OOTB ribbon button, there is a workaround that we can replace it with a custom button.
Here is a documentation about Replacing a Button on the Server Ribbon:
http://msdn.microsoft.com/en-us/library/ff407619.aspx
Another two links about create a custom ribbon button for your reference:
http://msdn.microsoft.com/en-us/library/office/ff407458(v=office.14).aspx
http://sharepoint.stackexchange.com/questions/20646/attach-a-javascript-function-to-an-ootb-ribbon-button
Best regards
Patrick Liang
TechNet Community Support