<ul>
  <li>list item 1</li>
  <li>list item 2</li>
  <li>list item 3</li>
  <li>list item 4</li>
  <li>list item 5</li>
</ul>

{
  const ex1 = $('li').eq(2)
  const ex2 = $('li').eq(-2)
  
  console.log(ex1)
  console.log(ex2)
}

{
  const ex1 = document.querySelectorAll('li')[2]
  const ex2 = Array.from(document.querySelectorAll('li')).at(-2)
  
  console.log(ex1)
  console.log(ex2)
}