兼容ie9以下的polyfill类库

1、fetch： https://github.com/github/fetch

2、HTML5 History/State APIs (pushState, replaceState, onPopState)：https://github.com/browsersta...

3、REM unit polyfill：
https://github.com/chuckcarpe...

4、HTML5 Cross Browser Polyfills：
HTML5 Cross Browser Polyfills

5、html5shiv：https://github.com/aFarkas/ht...

6、selectivizr：
兼容css3的新选择器伪元素等

7、fastclick：
Polyfill to remove click delays on browsers with touch UIs