SOURCE

let log = console.log;
function date2Ymd(timestamp=0) {
    timestamp = timestamp ? (new Date).getTime() + timestamp * 1e3 : undefined;        
    let dateHand = timestamp?new Date(timestamp):new Date();
    let month = (dateHand.getMonth() + 1);
    month = month < 10 ? `0${month}` : month;
    let date = dateHand.getDate();
    date = date < 10 ? `0${date}` : date;
    return (dateHand.getFullYear() + '-' + (month) + '-' + date)
}
console.log(date2Ymd());
console.log(date2Ymd(86400))