title: Spread Syntax ES6
body: <p>Consider the following sample code</p>
  <pre><code>var x = [&quot;a&quot;, &quot;b&quot;, &quot;c&quot;];
  var z = [&quot;p&quot;, &quot;q&quot;];
  
  var d = [...x, ...z];
  
  var e = x.concat(z);
  </code></pre>
  <p>Here, the value of <code>d</code> and <code>e</code> are exactly same and is equal to  <code>[&quot;a&quot;, &quot;b&quot;, &quot;c&quot;, &quot;p&quot;, &quot;q&quot;]</code>, so,</p>
  <ol>
  <li>What exactly is the difference between these two?</li>
  <li>Which one is more efficient and why?</li>
  <li>What exactly is the use of spread syntax?</li>
  </ol>