title: how to count frequency in two array by ES6
body: <p>Frequency of a string in an array of strings
  Create a function you are given a collection of strings and a list of queries. For every query there is a string given. We need to print the number of times the given string occurs in the collection of strings.</p>
  
  <p>Examples:</p>
  
  <ul>
  <li><p>Input : </p>
  
  <pre><code>a[] = [wer, tyu, uio]
  b[] = [wer, wer, tyu, oio, tyu]
  </code></pre></li>
  <li><p>Output : <code>[2 2 0]</code></p></li>
  </ul>
  
  <p>Explanation : 
  <code>a[0]</code> appears two times in <code>b[]</code></p>