##微信支付接口列表
### 公众号支付API列表（境内服务商版）`wepay.js`
参考地址： https://pay.weixin.qq.com/wiki/doc/api/jsapi_sl.php?chapter=9_4
1. ✔统一下单 `async unifiedOrder (params)`
2. ✔查询订单 `async orderQuery (params)`
3. ✔关闭订单 `async closeOrder (params)`
4. ✔申请退款 `async refund (params)`
5. ?查询退款 `async refundQuery (params, callback)`
6. ?下载对账单 `async downloadBill (params)`
7. ✔支付结果通知 `notify_url`
8. 交易保障 
9. ?退款结果通知 `notify_url`