How to create an array/object from an ordered list?

How can I create an array from an ordered list, with the number as the index/key and the list item as the array value?

Example list:

<ol>
  <li>First list item</li>
  <li>Second list item</li>
  <li>Third list item</li>
</ol>

Should result in:

{"1" => "First list item", "2" => "Second list item", "3" => "Third list item"}

I tried using Array.from() with a few variations but that didn't work