实现扫码枪扫描二维码

扫码枪扫描二维码

业务需求要将数据生成二维码，并用扫码枪扫出数据上传到服务端。
先上代码吧，之后再完善注意点

this.start = new Date().getTime()

    let code = ''
    let lastTime, nextTime
    let lastCode, nextCode
    let that = this
    window.document.onkeypress = function (e) {
      if (window.event) { // IE
        nextCode = e.keyCode
      } else if (e.which) { // Netscape/Firefox/Opera
        nextCode = e.which
      }
      console.time()
      console.log('nextCode', nextCode)
      if (e.which === 13) {
        if (code.length < 3) return // 手动输入的时间不会让code的长度大于2，所以这里只会对扫码枪有
        console.log(code)
        console.log('扫码结束')
        console.timeEnd()

        that.parseQRCode(code) // 获取到扫码枪输入的内容，做别的操作
        code = ''
        lastCode = ''
        lastTime = ''
        return
      }
      nextTime = new Date().getTime()
      if (!lastTime && !lastCode) {
        console.log('扫码开始。。。')
        code += e.key
      }

      if (lastCode && lastTime && nextTime - lastTime > 500) { // 当扫码前有keypress事件时,防止首字缺失
        console.log('防止首字缺失。。。')
        code = e.key
      } else if (lastCode && lastTime) {
        console.log('扫码中。。。')
        code += e.key
      }
      lastCode = nextCode
      lastTime = nextTime
    }