title: Set JavaScript variable = null, or leave undefined?
body: <p>When declaring variables at the top of the JavaScript function, is it best practice to set them equal to null, or leave as 'undefined'? Another way to ask, what circumstances call for each option below?</p>
  
  <p>Option A:</p>
  
  <pre><code>var a = null,
      b = null;
  </code></pre>
  
  <p>Option B:</p>
  
  <pre><code>var a,
      b;
  </code></pre>