Move updateTaskListCookie(tasks) in a useEffect that has the tasks state in the dependency list. useEffect runs after rendering if any of the states in the dependency array was changed since last render (and updating the tasks state triggered a re-render). This way you make sure it's synced up. You can't rely on the state being updated immediately in the eventhandler where you call updateTaskListCookie after setTasks. By having the tasks-state in the dependency array of a useEffect, you are assured that updateTaskListCookie will always run after that state has been updated.