合单JSAPI支付

使用合单支付接口，用户只输入一次密码，即可完成多个订单的支付。目前最多一次可支持50笔订单进行合单支付。 官方文档

const { Formatter, Rsa } = require('wechatpay-axios-plugin')

wxpay.v3.combineTransactions.jsapi.post({
  combine_appid,
  combine_mchid,
  combine_out_trade_no,
  scene_info,
  sub_orders,
  combine_payer_info,
  time_start,
  time_expire,
  notify_url,
  limit_pay,
})
.then(({ data: { prepay_id } }) => {
  const nonceStr = Formatter.nonce();
  const timeStamp = '' + Formatter.timestamp();
  const packageStr = 'prepay_id=' + prepay_id;
  return { 
    appId,
    timeStamp,
    nonceStr,
    package: packageStr,
    signType: 'RSA',
    paySign: Rsa.sign(
      Formatter.joinedByLineFeed(appId, timeStamp, nonceStr, packageStr),
      merchantPrivateKeyInstance
    )
  }
})