title: Question about merge array using Array.push();
body: <p>I have two array:</p>
  <pre><code>let myArray1 = [1, 2, 3];
  let myArray2 = [9, 5, 6];
   
  </code></pre>
  <p>I try to merge the two array and save to a new array using push. I am aware that I can easily do it with concat. But I want to understand more about the code.</p>
  <pre><code>let myArray1 = [1, 2, 3];
  let myArray2 = [9, 5, 6];
  
  let myArray3 = myArray1.push(myArray2); // Result 4
  </code></pre>
  <p>I don't understand why it is 4 for the output?</p>