title: Add HTML control(s) via javascript
body: <p>Something is eluding me ... it seems obvious, but I can't quite figure it out.</p>
  
  <p>I want to add/remove a couple of HTML controls to a page (plain old html) when a user changes value of a dropdown list.  An example is to add or remove a "number of guests in this room" textbox for each (of a number) of rooms requested ... </p>
  
  <p>So if a user selects:</p>
  
  <p>1 room, there is one text box</p>
  
  <p>2 rooms, there are two text boxes</p>
  
  <p>3 rooms, three text boxes </p>
  
  <p>back to 2 rooms, two text boxes</p>
  
  <p>and so on ...</p>