placeholder change on conditions

Hi I'd like to change the message placeholder text on a radio button selection, is it possible with the actual condition mechanism of jotform?

It is not possible. You may however use two different fields for that and define the placeholder on each fields under its properties. Then use show/hide condition to trigger the fields with the corresponding placeholder base on the drop down selection. That's so far the easiest workaround without going through the form source code.

Example: http://form.jotformpro.com/form/52195140040947?

Let us know if you have further questions. Thanks!