1、什么是虚拟dom（VNode）？
https://github.com/answershuto/learnVue/blob/master/docs/VNode%E8%8A%82%E7%82%B9.MarkDown
2、源码keep-alive.js中Object.create(Null)是什么意思？
https://blog.csdn.net/blueblueskyhua/article/details/73135938
https://segmentfault.com/q/1010000009976954
3、vue中的diff算法，如何理解？
https://www.jianshu.com/p/22f82cc60285