Node.js 打通微信小程序支付

// index.js
// 获取应用实例
const app = getApp()

Page({
  // ...
  handlePay() {
    wx.request({
      url: 'http://192.168.1.3:3000/pay',
      success(res) {
        wx.requestPayment({
          nonceStr: res.data.nonceStr,
          package: res.data.package,
          signType: res.data.signType,
          paySign: res.data.paySign,
          timeStamp: res.data.timeStamp,
        })
      },
    })
  },
  // ...
})

const Koa = require('koa')
const axios = require('axios')
const md5 = require('md5')
const {js2xml, xml2js} = require('xml-js')

const app = new Koa()

app.use(async ctx => {
  const dict = {
    xml: {
      body: 'JSAPI支付测试',
      appid: '你的小程序 id',
      mch_id: '商户 id',
      nonce_str: generateNonceStr(), // 随机字符串，长度要求在32位以内。调用随机数函数生成，将得到的值转换为字符串
      notify_url: 'http://127.0.0.1/notify',
      openid: '支付用户的 openid', // 懒得做登录系统了
      out_trade_no: '3783-6c16-4fab-83ff-6f193d70111', // 商户系统内部订单号，要求32个字符内，只能是数字、大小写字母_-|*且在同一个商户号下唯一
      spbill_create_ip: '127.0.0.1',
      total_fee: 10, // 订单总金额，单位为分
      trade_type: 'JSAPI',
    }
  }

  let str = ""
  Object.keys(dict.xml).sort().forEach(key => {
    if (str === '') {
      str += `${key}=${dict.xml[key]}`
    } else {
      str += `&${key}=${dict.xml[key]}`
    }
  })

  str += '&key=' + '你的 key'

  const sign = md5(str)
  dict.xml.sign = sign.toUpperCase()

  const d = js2xml(dict, {compact: true, ignoreComment: true, spaces: 2})

  const res = await axios.post('https://api.mch.weixin.qq.com/pay/unifiedorder', d, {
    headers: {
      "Content-Type": "text/xml",
    },
  })

  const data = xml2js(res.data, {compact: true})

  const clientDict = {
    appId: '你的小程序 id',
    timeStamp: Math.floor(Date.now()/1000).toString(),
    nonceStr: generateNonceStr(),
    package: 'prepay_id=' + data.xml.prepay_id._cdata,
    signType: 'MD5',
  }

  str = ''
  Object.keys(clientDict).sort().forEach(key => {
    if (str === '') {
      str += `${key}=${clientDict[key]}`
    } else {
      str += `&${key}=${clientDict[key]}`
    }
  })

  str += '&key=' + '你的 key'
  clientDict.paySign = md5(str)

  ctx.body = clientDict
})

function generateNonceStr() {
  return Math.random().toString().slice(2)
}

app.listen(3000)