title: How to validate 4 digit USA zip code?
body: <p>I want to validate USA zip codes and I have used these regex:</p>
  
  <pre><code>/(^\d{5}$)|(^\d{5}-\d{4}$)/.test(value); //First
  /^\b\d{5}(-\d{4})?\b$/.test(value); //Second
  /^\d{5}(-\d{4})?(?!-)$/.test(value); //Third
  /^\d{5}(?:[-\s]\d{4})?$/.test(value); //Fourth
  </code></pre>
  
  <p>I tested <a href="http://www.mapsofworld.com/usa/zipcodes/result.php" rel="nofollow">here</a>, <a href="http://www.unitedstateszipcodes.org/" rel="nofollow">here</a>, and <a href="http://www.city-data.com/zips/zipdir/dir0.html" rel="nofollow">here</a> that the USA zip codes start at 1001. Apparently, using either of the regex above accepts "00000" because it has 5 digits?</p>
  
  <p>Ultimately, I want it to accept 4 digits zip code that starts in 1001. Is my regex correct?</p>