title: Javascript: Check the URL is working / existed / reachable (returning Status 200 / non-broken) or not
body: <p>With Javascript, i want to check a URL is reachable (existed, returning with HTTP Status 200, NOT 404, etc).</p>
  
  <p>Let's say, how to know (by using JS) that:</p>
  
  <ul>
  <li>"<a href="https://www.google.com" rel="nofollow">https://www.google.com</a>" (WebSite) .. is a reachable link. </li>
  <li>And, "<a href="http://code.jquery.com/jquery-1.11.3.min.js" rel="nofollow">http://code.jquery.com/jquery-1.11.3.min.js</a>" (JS File) .. is also a reachable link.</li>
  <li>And, "<a href="https://www.microsoft.com/library/errorpages/Images/Microsoft_logo.png" rel="nofollow">https://www.microsoft.com/library/errorpages/Images/Microsoft_logo.png</a>" (Image) also is reachable.</li>
  </ul>
  
  <p>(They are NOT: broken, non-existed, 404, etc).</p>
  
  <hr>
  
  <p>Again how to know, such:</p>
  
  <ul>
  <li>"<a href="http://www.asderafsdfefrasdfsdfasf.com" rel="nofollow">http://www.asderafsdfefrasdfsdfasf.com</a>"</li>
  <li>Or, "<a href="https://www.google.com/xxxxxxxxxxx.js" rel="nofollow">https://www.google.com/xxxxxxxxxxx.js</a>" ..</li>
  </ul>
  
  <p>are <strong>BROKEN, not-reachable, non-existed, 404</strong>, etc?</p>