title: When should a period be used after $ in jQuery?
body: <p>I am a beginner in JQuery.</p>
  
  <p><strong>When should the dot after $ be used?</strong></p>
  
  <p><code>$.trim(str)</code> and not <code>$trim(str)</code>? </p>
  
  <p>And some cases without point: <code>$(document).ready</code>, but not <code>$.(document).ready</code>?</p>
  
  <p>Thanks.</p>