How to display a 3-minute countdown using js and output the specified number

function?timeshow(){

var?time?=?3;//s

var?start?=?window.setInterval(function( ){

time?=?time?-?1;

console.log(time);

document.getElementById('show').innerHTML ='Timer starts, '+time+'jump after seconds!';

if(time?==?0){

window.clearInterval(start);

document.getElementById('show').innerHTML='Timeout';

}

},1000);

}