wx.scanQRCode({

            onlyFromCamera: true,

            needResult: 1,

            scanType: ["qrCode"],

            success: function(res) {

              // alert("开始识别二维码成功")

              // console.log(res);

              // alert(JSON.stringify(res));

              var result = res.resultStr;

            },

            fail: function(res) {

              // alert("开始识别二维码失败")

              console.log(res);

              // alert(JSON.stringify(res));

            }

          });