JS 如何获取扫码枪输入数据

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

1. 扫码枪扫描到的条形码每一位会触发一次onkeydown事件
2. 比如扫描条码位‘1234567890'的条形码，会连续执行10次onkeydown事件
3. 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

到此这篇关于js 获取扫码枪输入数据的文章就介绍到这了,