js data no formato aaaa-mm-dd
yourDate.toISOString().split('T')[0]
Formato De Data / Hora.Agora para aaaa-mm-dd c#
var dateString1 = DateTime.Now.ToString("yyyyMMdd");
var dateString2 = DateTime.Now.ToString("yyyy-MM-dd");
Console.WriteLine("yyyyMMdd " + dateString1);
Console.WriteLine("yyyy-MM-dd "+ dateString2);
Converter uma data para aaaa mm dd
const formatYmd = date => date.toISOString().slice(0, 10);
formatYmd(new Date());
python data de dd/mm/aa para aa-mm-dd
lastconnection = datetime.strptime("21/12/2008", "%d/%m/%Y").strftime('%Y-%m-%d')
python datetime no formato aaaa-mm-dd
from datetime import datetime
now = datetime.today().isoformat()
print(now) # '2018-12-05T11:15:55.126382'