i was just playing around with HTML5 input type=number. while its not supported by all browsers I expect it is the way going forward to handle type specific handling (number for ex). pretty simple to do with razor (ex is VB)
@Html.TextBoxFor(Function(model) model.Port, New With {.type = "number"})
and thanks to Lee Richardson, the c# way
@Html.TextBoxFor(i => i.Port, new { @type = "number" })
beyond the scope of the question but you could do this same approach for any html5 input type