title: How to print out a nested array effectively in javascript?
body: <p>I have a nested array: </p>
  
  <pre><code>[1, 2, [3, 4, [5, [6]], 7], 8, 9]
  </code></pre>
  
  <p>How could I print it in an elegant way to look like this:</p>
  
  <pre><code>[1, 2, 3, 4, 5, 6, 7, 8, 9]
  </code></pre>