微信小程序调用支付接口的完整流程记录

 login() {
    var that=this
    wx.login({
      success(res) {
        console.log(res)
        wx.request({ url: '', 
        data: { code: res.code } })
      },
    })

      let {
        money,
        openId
      } = this.data
     
      let token = wx.getStorageSync('user_token')
      let openList = await request('/接口', {
        ...需要给后端的字段
        openid: openId
      })
      this.setData({
        prepay_id: openList.data.prepay_id
      })

let random = (Math.random()).toString() //这个随机数一定要变成字符串
      let timestamp = (new Date().getTime()).toString() //时间戳一定要是字符串
      let mch_key = 'FVmZcEmubX817JRKHmWo1vaVHzte2Oha'
      let obj = {
        appId: 'wxb9811d3b2e3De44c',
        nonceStr: random,
        package: "prepay_id=" + this.data.prepay_id,
        signType: 'MD5',
        timeStamp: timestamp
      }
      //参数名ASCII码从小到大排序（字典序）
      let arr = Object.keys(obj).sort().map(item => {
       return `${item}=${obj[item]}`;
      });
      //最后拼接上key（商户密钥）得到字符串
      let str = arr.join('&') + '&key=' + mch_key;
      console.log(str);
      //对str进行MD5运算，再将得到的字符串所有字符转换为大写
      let paySign = md5.hexMD5(str).toUpperCase()
      wx.requestPayment({
        "timeStamp": timestamp,
        "nonceStr": random,
        "package": "prepay_id=" + this.data.prepay_id,
        "signType": "MD5",
        "paySign": paySign,
        "success": function (res) {
          console.log('成功了');
        },
        "fail": function (res) {
          console.log(res);
          if (res.errMsg === 'requestPayment:fail cancel') {
            wx.showToast({
              title: '用户取消支付',
              icon: 'none',
              duration: 2000
            })
          } else {
            wx.showToast({
              title: res.errMsg,
              icon: 'none',
              duration: 2000
            })
          }
        },
      })