Make all elements with class draggable – draggable. Like a ball in the chapter.

Requirements:

• Use event delegation to track drag start: a single event handler on document for mousedown.
• If elements are dragged to top/bottom window edges – the page scrolls up/down to allow further dragging.
• There is no horizontal scroll (this makes the task a bit simpler, adding it is easy).
• Draggable elements or their parts should never leave the window, even after swift mouse moves.

The demo is too big to fit it here, so here’s the link.