var today = new Date();
var dt = today.getFullYear() + '.' + (today.getMonth() + 1) + '.' + today.getDate();
var tm = today.getHours() + ":" + today.getMinutes() + ":" + today.getSeconds();
document.write(dt + " " + tm);
/*
run:
2019.9.18 20:49:31
*/