Add new objects to the nested array in react

Question

I have an array like this

const [boxes, setBoxes] = useState([
{
  title: "Background",
  id: 0,
  items: [],
},
]);


  const [selectedBox, setSelectedBox] = useState(0);

I want to add a new object in items field and copy the past ones,

This is what I'm trying

setBoxes(prevState => {
  return [
    ...prevState,
    prevState[selectedBox].items: [...prevState[selectedBox].items, {title:"test"}]      
  ]
})

Thanks a lot, have a nice day

Answer 1

Not sure what you are trying to do exactly due to the lack of information but you can try something like this:

setBoxes(prevState => {
  const newBoxes = {
    ...prevState,
  };
  newBoxes[selectedBox].items = [
    ...newBoxes[selectedBox].items,
    { title: 'test' },
  ];
  return newBoxes;
})