I currently have a state like so:

```
  const [startDate, setStartDate] = useState({
    bDay: new Date(),
    anniversary: new Date(),
  });

```

Let us suppose I want to retain bDay and change anniversary date would I need to copy the previous state to change only part of it?

Like so:

```
    setDropdowns(prevState => ({
    ...prevState,
    anniversary: new Date(datefrom4yearsago) 
  }))

```

or can I just set the state for only the one I want and the state will be kept the same for all other object entries?

```
setDropdowns({anniversary: new Date(datefrom4yearsago)})

```