React useEffect doesn't trigger when array in an object state changes-CodePudding

The scenario is that there is an object state with an array in it. I want useEffect to be executed when values are added or changed in it. I tried a few solutions but none of them worked.

       const [filter, setFilter] = useState({})
       const firstUpdate = useRef(true);

    useEffect(() => {
    
        console.log("Filter Updated")
        if (firstUpdate.current) return firstUpdate.current = false;
          
        // API  Calls Here
        
      }, [filter])


const handler = (categoryName, categoryId) => {
    let x = filter;
    x.categoryIDs = [categoryId];
    setFilter(x)
    
  }

CodePudding user response：

React compares by reference. You simply modify a property of an object and use that in the new state, this wont work.

Try setFilter({...x}).