title: Javascript - modify a specific part of an array
body: <p>I am a real beginner and I started to learn java script,
  I am following a course and I am trying to reproduce a step in Visual Studio but when I run the code I get no result.</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>var myArray = [10, 20, 30];
  myArray[1] = 25; // myArray now equals to 10, 25, 30
  console.log(myArray)</code></pre>
  </div>
  </div>
  </p>
  <p>when running this myArray should go from 10,20,30 to 10,25,30
  but instead nothing happens, not even an error.
  Other parts of the code I write do give me an answer, so is not an issue with Visual Studio.</p>
  <p>Can you see what I do wrong?
  Thanks a lot
  Nic</p>