Create 5 star icons. On hover, highlight up to the hovered star. On click, lock the rating. Support half-stars with a clip or two separate icons. Add keyboard support (arrow keys to change, enter to select). Reset on mouse leave if not clicked.

Use a tree data structure. Write a recursive render function. Each comment has reply, vote, and collapse handlers. Indent nested comments by depth. Handle reply (add a child), vote (update score), and collapse (toggle children).

Use the HTML Drag and Drop API: dragstart (store the dragged item index), dragover (prevent default to allow drop), drop (reorder the array). Update the data and re-render. Add visual feedback (highlight the drop target).