How can I apply a dynamic mask in an dynamic form?

Question

I have a problem with my dynamic form. This input is:

Answer 1

Pamio is on the right track. But appending the script to the page doesn't seem to work(?). The following works for me:

$('#plusPhone').click(function(){
   var HTML = 'this contains an input field with the class you want to mask';
   jQuery('#element-you-want-to-append-to').append(HTML);
   jQuery('.class-you-want-masked').mask('99-99-9999');
   //Just call the mask AFTER appending the input, and it should be applied.
)};