Common Beginner Mistakes with React(joshwcomeau.com)

  React.useEffect(() => {
    async function runEffect() {
      // Effect logic here
    }
    runEffect();
    return () => {
      // Cleanup logic here
    }
  }, [userId]);

    const [state, setState] = useHook("a")

    ...

    setState("b")
    console.log(state)

   const [accessor, setState] = useSignal("a")

   ...

   setState("b")
   console.log(accessor())

  function handleAddItem(value) {
    const nextItems = [...items, value];
    setItems(nextItems);
  }

  function handleAddItem(value) {
    setItems(items => [...items, value]);
  }

   export function deepClone<T>(obj: T): T {
       if (obj == null || typeof obj !== 'object')
           return obj;

       const clone = new (obj as any).constructor();

       for (let key in obj) {
           if (obj.hasOwnProperty(key))
               clone[key] = deepClone(obj[key]);
       }

       return clone;
   }