title: if (jQuery)(function ($) { . . .})(jQuery); plugin format
body: <p>I was looking at a plugin that has the format</p>
  
  <pre><code>if (jQuery)(function ($) { 
          -- plugin code --
  })(jQuery);  
  </code></pre>
  
  <p>I understand that</p>
  
  <pre><code>(function ($) { 
          -- plugin code --
  })(jQuery);  
  </code></pre>
  
  <p>is to make sure that $ refers to jQuery and not Prototype inside our function, but what does the </p>
  
  <pre><code>if (jQuery)
  </code></pre>
  
  <p>do for us?</p>
  
  <p>Thanks</p>