扫码枪是模拟的键盘输入，所以用键盘事件window.document.onkeypress = function(e){ }.

在vue项目中，可以在created/mounted中做

上代码：

<template>
  <el-input  v-model="codeValue" placeholder="请输入条形码"/>
</template>

<script>
export default {
  data() {
    return {
      codeValue: '',
      code: '',
      lastTime: '',
      nextTime: '',
      lastCode: '',
      nextCode: '',
      dtmainId: ''
    }
  },
  created() {
    window.document.onkeypress = (e) => {
      if (window.event) { // IE
        this.nextCode = e.keyCode
      } else if (e.which) { // Netscape/Firefox/Opera
        this.nextCode = e.which
      }

      if (e.which === 13) { // 键盘回车事件
        if (this.code.length < 3) return // 扫码枪的速度很快，手动输入的时间不会让code的长度大于2，所以这里不会对扫码枪有效
        console.log('扫码结束。')
        console.log('条形码：', this.code)
        this.parseQRCode(this.code) // 获取到扫码枪输入的内容，做别的操作
        this.lastCode = ''
        this.lastTime = ''
        return
      }

      this.nextTime = new Date().getTime()
      if (!this.lastTime && !this.lastCode) {
        this.code = '' // 清空上次的条形码
        this.code += e.key
        console.log('扫码开始---', this.code)
      }
      if (this.lastCode && this.lastTime && this.nextTime - this.lastTime > 500) { // 当扫码前有keypress事件时,防止首字缺失
        this.code = e.key
        console.log('防止首字缺失。。。', this.code)
      } else if (this.lastCode && this.lastTime) {
        this.code += e.key
        console.log('扫码中。。。', this.code)
      }
      this.lastCode = this.nextCode
      this.lastTime = this.nextTime
    }
  },
  methods: {
    parseQRCode(code) {
      if (code.length === 13) {
        // 处理自己的逻辑
        this.$emit('barCode', code) //通知父组件
      } else if (code.length === 23) {
        console.log('B类条码:' + code)
      } else if (code.length === 0) {
        console.log('请输入条码！')
      } else {
        alert('条码不合法：' + code)
      }
      this.codeValue = code
    }
  }
}
</script>