title: How is this array joining a string?
body: <p>Question about delimiter :</p>
  <pre><code>console.log(Array(2).join('a'));
  console.log(['', '', ''].join('a'));
  </code></pre>
  <p>Why does the above code only return:</p>
  <pre><code>a
  aa
  </code></pre>
  <p>instead of:</p>
  <pre><code>aa
  aaa
  </code></pre>
  <p>Array(2) creates an array with two empty or undefined elements in an array [undefined, undefined], so shouldn’t it output <code>aa</code>?</p>