title: Automatically adding a colon to a string (e.g. 0800 to 08:00)
body: <p>I want to transform a string like "0800" automatically to "08:00".</p>
  
  <p>So I thought that way: If I type in the running program 2 digits, after typing the third the colon should automatically appear between the second and third digit. Without refreshing or something.</p>
  
  <p>Has anyone a solution for me?</p>