title: Get duplicate characters count in a string
body: <p>Can anyone help me to get the count of repeated characters in a given string in javascript. </p>
  
  <p>For example,</p>
  
  <pre><code>"abccdef" -&gt; 1 (Only "c" repeated)
  
  "Indivisibilities" -&gt; 2 ("i" and "s" repeated)
  </code></pre>
  
  <p>Thank You</p>