I am trying to append data in field using javascript.

I have this object :

{
  id: 1,
  time: 12:10:09,
}

and I have this date : 2021-12-01

I want to append this date to time.

object after append :

{
  id: 1,
  time: 2021-12-01 12:10:09,
}

date (space) time.

I tried:

object.time = date + " " + object.time;

but I don't think this is the best solution

Any suggestion?