js如何获取扫码枪输入数据

 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; }

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; } } }