title: Return join vs return string
body: <p>I saw this example and wondered why anyone would do it:</p>
  
  <pre><code>function a(str) {
    return [
      '&lt;div&gt;',
       str,
      '&lt;/div&gt;'
    ].join('');
  }
  </code></pre>
  
  <p>Isn't it an equivalent to the following code and what's the advantages / disadvantages of using just:</p>
  
  <pre><code>function a(str) {
    return '&lt;div&gt;' +
       str +
      '&lt;/div&gt;;
  }
  </code></pre>
  
  <p>Thank you.</p>