Slide slides seamlessly (no need to reset the subscript)

The effect of the code can be directly read the article at the bottom of the presentation address, before the slide slide I wrote a small bug is when the last node, but also need to go back to the first node. Go back to the first node from the last one. This process is a waste of time. and not friendly. Now, every time I do this, I write a callback function, the DOM operation puts the first one on the last one, and it becomes a seamless slide.

<!           DOCTYPE html>
Demo Address: Http://runjs.cn/detail/crxcxlbo
Slide slides seamlessly (no need to reset the subscript)