title: Why javascript is not well constructing my date
body: <p>In my Angular 6 project, I have the following code:</p>
  
  <pre><code>const date1 = new Date(2018, 9, 17);
  console.log('date1 = ', date1);
  </code></pre>
  
  <p>But I get the following result in the cosole of my browser:</p>
  
  <pre><code>date1 =  Wed Oct 17 2018 00:00:00 GMT+0200 (Central European Summer Time)
  </code></pre>
  
  <p>Why do I get Oct but not Sept?</p>