版本：
文件：
- https://cdn.bootcdn.net/ajax/libs/feature.js/1.1.3/feature.js
- https://cdn.bootcdn.net/ajax/libs/feature.js/1.1.3/feature.min.js
Feature.js is a fast, simple and lightweight browser feature detection library. It has no dependencies and weighs only 1kb minified and gzipped.