注意事项：
1 Note that native HTML element names start with a lowercase letter, while custom React class names begin with an uppercase letter.
疑问：
Notice how we‘re mixing HTML tags and components we‘ve built. HTML components are regular React components, just like the ones you define, with one difference. The JSX compiler will automatically rewrite HTML tags to React.createElement(tagName)expressions and leave everything else alone. This is to prevent the pollution of the global namespace.（哪来的全局变量？）
原文：http://www.cnblogs.com/a198/p/5591874.html