title: alert if input val = NaN?
body: <p>I know this question might have been asked a lot of times but I don't really get the function <code>isNan()</code>. I have a calculator and if the result is "NaN" (for example 0 divided by 0), I want to alert 'Doesn't work!'. I thought of something like:</p>
  
  <pre><code>function Error() {
      if ($('#result').val() == NaN) {
          alert.('Doesn't work!');
      }
  };
  </code></pre>
  
  <p>The result is in the input with the #result. How do i use isNan() here? Can someone help me please? Thanks for responding and sorry for the same question again.</p>