Challenge Solution in "Updating Arrays in State" Page Uses Mutation

For the solution to the third challenge in the Updating Arrays in State page, it uses the following function:

function handleAddTodo(title) {
  setTodos([
    ...todos,
    {
      id: nextId++,
      title: title,
      done: false
    }
  ]);
}

This changes nextId, a variable outside the component's scope, which I believe is a mutation. It should instead use the length of todos to set the next id.

从链接的“Updating Arrays in State”页面开始，检查第三个挑战的解决方案，尤其是 handleAddTodo 函数及其对 nextId 的使用。更新示例，使其不会改变组件外部的变量，然后验证挑战解决方案仍会生成预期的 todo ID。