title: How to format numbers by prepending 0 to single-digit numbers?
body: <p>I want to format a number to have two digits. The problem is caused when <code>0</code>–<code>9</code> is passed, so I need it to be formatted to <code>00</code>–<code>09</code>.</p>
  
  <p>Is there a number formatter in JavaScript?</p>