h5页面实现扫码功能

var video = document.querySelector(".bar_video");
var canvas = document.createElement("canvas");
var context = canvas.getContext("2d");
canvas.width = 640;
canvas.height = 480;
var constraints = { video: { facingMode: "environment" } };
navigator.mediaDevices
  .getUserMedia(constraints)
  .then(function (mediaStream) {
    video.srcObject = mediaStream;
    video.onloadedmetadata = function (e) {
      video.play();
    };
  })
  .catch(function (err) {
    console.log(err.name + ": " + err.message);
  });
setInterval(function () {
  context.drawImage(
    video,
    0,
    0,
    (canvas.width = video.videoWidth),
    (canvas.height = video.videoHeight)
  );
  var image = canvas.toDataURL("image/png");
    $.ajax({
        url: "/product/code",
        type: "post",
        data:{
            phoneCode:image
        },
        success:function(res) {
         
          
        },
        error:function (err) {
           console.log(err) 
        }
      })
  
}, 5000);

            imgbase = kw.get("phoneCode")  # 接受的图片
            imgbase=imgbase.split(",")[1]
            imgdata = base64.b64decode(imgbase)#解码
            url =os.path.join(os.path.abspath(os.path.dirname(__file__)),"0.png")
            file = open(url, 'wb')#保存为0.png的图片
            file.write(imgdata)
            file.close()
            image=cv2.imread(url)
            gray = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
            texts = pyzbar.decode(gray)
            print(texts)
            if texts == []:
               return json.dumps({"state": 400})
            for text in texts:
                code = text.data.decode("utf-8")
                print(code)