title: Pad a number with leading zeros in JavaScript
body: <p>In JavaScript, I need to have padding.</p>
  
  <p>For example, if I have the number 9, it will be "0009". If I have a number of say 10, it will be "0010". Notice how it will always contain four digits.</p>
  
  <p>One way to do this would be to subtract the number minus 4 to get the number of 0s I need to put.</p>
  
  <p>Is there was a slicker way of doing this?</p>