title: Replace underscores on typing input in JavaScript
body: <p>I have a text field with little dashes/underscores as shown in the image. How do I use JavaScript/backbone.js to make these dashes to be replaced by the input number upon typing?
  As I type, I want the underscore to be replaced with the number I type. How do I achieve this?</p>
  <p>Thanks in advance</p>
  <p><a href="https://i.stack.imgur.com/dXFgk.jpg" rel="nofollow noreferrer">input invoice field</a></p>