版本：
文件：
- https://cdn.bootcdn.net/ajax/libs/knockout-es5/0.4.6/knockout-es5-clean.js
- https://cdn.bootcdn.net/ajax/libs/knockout-es5/0.4.6/knockout-es5-clean.min.js
- https://cdn.bootcdn.net/ajax/libs/knockout-es5/0.4.6/knockout-es5.js
- https://cdn.bootcdn.net/ajax/libs/knockout-es5/0.4.6/knockout-es5.min.js