title: Javascript/jQuery - input with some pre-filled characters on some positions, and other empty ready-to-fill positions
body: <p>Is it possible to have an input of type text, having preset on position 3 and 6 a pre-defined character, like '$' for example, and then allowing to fill positions 1,2,4,5,7,8,9 and 10 with any other character?</p>
  
  <p>So for example, when the user opens the page and first sees this input, the stuff displayed in the input
  would be: <br>
  <code>_ _ $ _ _ $ _ _ _ _</code> <br>
  and he can only fill those positions marked with "_".</p>
  
  <p>Thanks in advance!</p>