I have a dynamic action, basic flow as show below. I think I have something round the wrong way. I hope I have explained this correctly below.

The process is very simple
1. Execute some PLSQL, This basically goes off and builds a bunch of CSV files within a zip file.
2. The PLSQL returns javascript (Which for debugging I display in P4_URL) E.G.
javascript : var x=window.open('[http://mydomain.com/tmp_files/CSV_02142017140250.zip','_blank');](http://mydomain.com/tmp_files/CSV_02142017140250.zip','_blank');)
3. I want to run this javascript ?? But I cant get it to trigger no matter how I organize it. The javascript is correctly formed as it runs when cut and pasted directly into the address bar.
I tried setting the button as a redirect to URL, but that fires before the submit .
I cant add a process as there are multiple submit actions on the page