title: Why variable with length of array in it doesn't change after push?
body: <p>why the <code>arrLength</code> variable doesn't change it's value after the push?</p>
  <pre><code>const arr = [1,2,3]
  
  let arrLength = arr.length
  
  arr.push(4)
  
  console.log(arrLength)
  </code></pre>