版本：1.8.6
- https://cdn.bootcdn.net/ajax/libs/nvd3/1.8.6/nv.d3.css
- https://cdn.bootcdn.net/ajax/libs/nvd3/1.8.6/nv.d3.js
- https://cdn.bootcdn.net/ajax/libs/nvd3/1.8.6/nv.d3.min.css
- https://cdn.bootcdn.net/ajax/libs/nvd3/1.8.6/nv.d3.min.js
A reusable charting library written in d3.js