Changing the destination page value based on user input on p

I want to force the portal page to a specific destination(s) based on user input. (instead of/overriding using the portal page destination setting in the page properties) Is there anyway to access the value that is assigned to the submit destination value? I want to change/set that value with javascript to re-direct them on save/submit to a specific create object portal page. So, if they choose "A" then they will go to page 1 and if they choose "B" then they will go to page 2. (both Create Object pages for different objects)