javascript converter a data para aaaa-mm-dd
// `date` is a `Date` object
const formatYmd = date => date.toISOString().slice(0, 10);
// Example
formatYmd(new Date()); // 2020-05-06
como converter-se nova data para dd/mm/aaaa em javascript
var todayDate = new Date().toISOString()
console.log(todayDate);