title: Javascript adding zeros to the beginning of a string (max length 4 chars)
body: <pre><code>var number = 1310;
  </code></pre>
  
  <p>should be left alone.</p>
  
  <pre><code>var number = 120;
  </code></pre>
  
  <p>should be changed to "0120";</p>
  
  <pre><code>var number = 10;
  </code></pre>
  
  <p>should be changed to "0010";</p>
  
  <pre><code>var number = 7;
  </code></pre>
  
  <p>should be changed to "0007";</p>