To get the date:
const date = new Date().toJSON().slice(0, 10)
console.log(date) //2015-07-23
For datetime:
const datetime = new Date().toJSON().slice(0, 19).replace('T', ' ')
console.log(datetime) //2015-07-23 11:26:00
Note that the resulting date/datetime will always be in the UTC timezone.