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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时间： 2020-06-08