how to customize success message on submit button in Microsoft Portals via javascript?

Hello everyone,

I am working with Microsoft Portals, I designed a Page Validator following this documentation https://docs.microsoft.com/en-us/dynamics365/customer-engagement/portals/add-custom-javascript

I have seen I can edit my custom Sucess Message on CRM via the Entity Forms record on the Additional Settings but it is not enough. I would like to edit this success message via JavaScript to include the value of a variable.

I am looking for obtain the following success message. "Thank you. An email has been sent to the email address <email address value> "

Being <email address value> a value introduced by the user one step before click the submit button. Is it possible?

Thank you very much in advance!