js获取USB扫码枪数据

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 = KaTeX parse error: Expected '}', got 'EOF' at end of input: … this.message(‘A类条码:’ + code);
} else if (code.length == 23) {
this.KaTeX parse error: Expected 'EOF', got '}' at position 38: …); }̲ else if (code.…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;
}
}
}