SOURCE

a = new Date();

function format(date) {
    m = date.getMonth().toString();
    if (m.length == 1) m = '0' + m;
    let d = date.getDate().toString();
    if (d.length == 1) d = '0' + d;
    return date.getFullYear() + '-' + m + '-' + d + ' ' + date.toTimeString().slice(0, 8);
}


console.log(format(a));