My solution for javascript list (disabling functionality buttons)

My Solution: https://w.trhou.se/olqht3o4o9

I personally didn't like the idea of a visual jump of buttons being added and created. I felt like it would give me a head ache to watch the buttons jump around. Additionally it would be a bad user experience if Up could be positioned where Down usually is. So instead I opted to 'gray out' and disable the buttons at the top and the bottom of the list.

Change Log from Original Script:

1. Refactored repeated code in Button creation to be an arrow function.
2. Created two functions to handle disabling & activating buttons.
3. Created a function to crawl through the list and then adds buttons if they need to be added and updates the buttons to reflect the list item's position ( could be optimized further for performance).
4. Created a function to create new list items
5. Created a new event listener that adds a list item on hitting the 'return' key within the input field.
6. Added crawl function to events to initialization of script & any listeners that affected order (addition / movement / subtraction)