https://codeburst.io/declarative-vs-imperative-programming-a8a7c93d9ad2
http://www.redotheweb.com/2015/09/18/declarative-imperative-js.html
https://msdn.microsoft.com/zh-tw/library/ff750239.aspx
https://msdn.microsoft.com/zh-tw/library/ff750239.aspx
https://stackoverflow.com/questions/33655534/difference-between-declarative-and-imperative-in-react-js
這是日劇《獻給阿爾吉儂的花束》裡常在放的古典樂，聽了讓人很靜心，不過其實它劇裡聽了會有點毛毛的。
if (true) {
let a = 40;
console.log(a); //40
}
console.log(a); // undefined
上面的范例，如果改成var的话，最下面一行的console.log(a); 却是可以获取到的（40）
Build with React JS
http://buildwithreact.com/tutorial
ReactJS Tutorial
https://www.tutorialspoint.com/reactjs/index.htm
React Native
https://facebook.github.io/react-native/docs/tutorial.html
Hello World – React
https://reactjs.org/docs/hello-world.html
文章
Optimizing React: Virtual DOM explained — Martian Chronicles, Evil Martians’ team blog
React Tutorial: A Comprehensive Guide to learning React.js in 2018
这里回传的 8,6,7,9 是字串的长度
dist
distribution