A js function that removes the value if exists and adds it if new

uniqueArr.js

const arr = YOUR_ARRAY
const newId = YOUR_NEW_ID; //new id

  if (!arr?.includes(newId)) {
    console.log("add now");

    arr?.push(newId); //adding to array because value doesnt exists
  } else {
    console.log("rem now");

    arr?.splice(arr.indexOf(newId), 1); //deleting
  }