Include example HTML5 Drag and Drop API

還沒有人認領這個 Issue。

There is a chapter called [“Drag'n'Drop with mouse events”](https://javascript.info/mouse-drag-and-drop), and it makes a passing reference to the Drag and Drop API. There are plenty of cases where it’s appropriate to choose this approach.

However, I think there also needs to be a “Drag'n'Drop with the API” chapter.

I’ve been using the DND API on a learning project. Although I got over the strange hurdle of learning which events apply to draggable items and which events apply to drop zones, I’m at a point where I am really missing the awesome guidance I can find on most other topics in your excellent work.

For the purpose of inspiration in creating such a chapter (or for anyone else reading this), one tutorial I found helpful helpful is this video (which includes the basics of the DND API, and implements a list-sorting feature):

https://www.youtube.com/watch?v=jfYWwQrtzzY

閱讀 https://javascript.info/mouse-drag-and-drop 上現有的「Drag'n'Drop with mouse events」章節，並查看所引用的教學影片，以評估其中對 HTML5 Drag and Drop API 的涵蓋情況。完成標準是新增一個解釋該 API 的章節，其中包括 draggable-item 和 drop-zone 事件，並提供何時使用它的實務指引。

由索引模型根據 Issue 內容生成。