title: Check for NaN, null and >=0 in one condition
body: <p>I have a var a;</p>
  
  <p>Its value can be <code>NaN, null and any +ve/-ve number including 0.</code></p>
  
  <p>I require a condition which filters out all the values of a such that only >=0 values yield a true in if condition.</p>
  
  <p>What is the best possible way to achieve this, I do not wish to use 3 different conditions joined using <code>||</code></p>