實現掃碼槍掃描二維碼

掃碼槍掃描二維碼

業務需求要將數據生成二維碼，並用掃碼槍掃出數據上傳到服務端。
先上代碼吧，以後再完善注意點

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 // 手動輸入的時間不會讓code的長度大於2，因此這裏只會對掃碼槍有
        console.log(code)
        console.log('掃碼結束')
        console.timeEnd()

        that.parseQRCode(code) // 獲取到掃碼槍輸入的內容，作別的操做
        code = ''
        lastCode = ''
        lastTime = ''
        return
      }
      nextTime = new Date().getTime()
      if (!lastTime && !lastCode) {
        console.log('掃碼開始。。。')
        code += e.key
      }

      if (lastCode && lastTime && nextTime - lastTime > 500) { // 當掃碼前有keypress事件時,防止首字缺失
        console.log('防止首字缺失。。。')
        code = e.key
      } else if (lastCode && lastTime) {
        console.log('掃碼中。。。')
        code += e.key
      }
      lastCode = nextCode
      lastTime = nextTime
    }