万一有人需要这样的：

使用draggable（）的handle选项可以解决问题。
例如，如果我有一个宽度为500px的div，我可以插入另一个（透明）div，它在右边对齐（例如）并且宽度为250px。然后我将最后一个div设置为可拖动div的句柄。

The problem can be solved by using the "handle" option of draggable(). For example, if I have a div with a width of 500px, I can insert another (transparent) div inside it aligned to the right (for example) and with a width of 250px. Then I set this last div as the handle of the draggable div.