1、扫码枪相当于键盘输入设备，输入一连串数字后加一个enter键。但在实际开发中需要区分是扫描枪输入还是键盘用户输入，区别在于扫码枪输入很快。

let code = ''; let lastTime, nextTime; let lastCode, nextCode; window.document.onkeypress = (e) => { if (window.event) { // IE nextCode = e.keyCode; } else if (e.which) { // Netscape/Firefox/Opera nextCode = e.which; } if (nextCode === 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); // 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) { code += e.key; } if (lastCode && lastTime && nextTime - lastTime > 30) { // 当扫码前有keypress事件时,防止首字缺失 code = e.key; } else if (lastCode && lastTime) { code += e.key; } lastCode = nextCode; lastTime = nextTime; }

PS：下面看下js获取USB扫码枪数据的代码

前言

找了很多相关的教程不太好用，汲取各家之长总结精简了一下

原理

扫码枪扫描到的条形码每一位会触发一次onkeydown事件

比如扫描条码位‘1234567890'的条形码，会连续执行10次onkeydown事件

条码扫描到最后一位，会直接触发Enter

需要引入jQuery，我这里用的是vue

window.onload = (e)=> { document.onkeydown = (e)=> { let nextCode,nextTime = ''; let lastTime = this.lastTime; let code = this.code; if (window.event) {// IE nextCode = e.keyCode } else if (e.which) {// Netscape/Firefox/Opera nextCode = e.which } nextTime = new Date().getTime(); //字母上方 数字键0-9 对应键码值 48-57; 数字键盘 数字键0-9 对应键码值 96-105 if((nextCode>=48&&nextCode<=57) || (nextCode>=96&&nextCode<=105)){ let codes = {'48':48,'49':49,'50':50,'51':51,'52':52,'53':53,'54':54,'55':55,'56':56,'57':57, '96':48,'97':49,'98':50,'99':51,'100':52,'101':53,'102':54,'103':55,'104':56,'105':57 }; nextCode = codes[nextCode]; nextTime = new Date().getTime(); } // 第二次输入延迟两秒，删除之前的数据重新计算 if(nextTime && lastTime && nextTime-lastTime>2000){ code = String.fromCharCode(nextCode); }else{ code += String.fromCharCode(nextCode) } // 保存数据 this.nextCode = nextCode; this.lastTime = nextTime; this.code = code; // 键入Enter if(e.which == 13) { // 判断 code 长度（这里就获取到条码值了，以下业务自由发挥） code = $.trim(code) if (code.length == 13) { this.$message('A类条码:' + code); } else if (code.length == 23) { this.$message('B类条码:' + code); } else if (code.length == 0) { this.$message('请输入条码'); } else{ this.$message('条码不合法：' + code); } //键入回车务必清空code值 this.code = '' return false; } }}

总结

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