let lastTime=''
let code=''
let timer=null
document.addEventListener('keydown',(e)=>{
let thisTime=new Date().getTime()
if(!lastTime){
lastTime=thisTime
code=e.key
}else{
if(thisTime-lastTime>10){
code=''
lastTime=''
}else{
code+=e.key
lastTime=thisTime
}
}
if(timer){
clearTimeout(timer)
}
timer=setTimeout(()=>{
if(code.length>3){
result=code
console.log(result)
}
lastTime=''
code=''
},20)
})