title: Fill array with reverse and forward of own elements
body: <p>I am trying to fill an array with up to 'n' values using its existing 4 values. I want to fill it with a sort of pattern that goes reverse and forward until it reaches the capacity of 'n' values. </p>
  
  <p>For example, with my array:</p>
  
  <pre><code>var array = [a, b, c, d];
  </code></pre>
  
  <p>I want the resulting array to follow this pattern:</p>
  
  <pre><code>array = [a, b, c, d,
           c, b, a, b, 
           c, d, c, b,
           a, b, c, d...(continues this pattern)]
  </code></pre>