javascript - react 中的支持实例是什么？

Question

尽管 React 文档中经常提到术语支持实例，但我无法理解它的含义。来自 react 文档:

To interact with the browser, you'll need a reference to a DOM node. You can attach a ref to any element, which allows you to reference the backing instance of the component. This is useful if you need to invoke imperative functions on the component, or want to access the underlying DOM nodes. link

This simplified component API is intended for components that are pure functions of their props. These components must not retain internal state, do not have backing instances, and do not have the component lifecycle methods. link

Because stateless functions don't have a backing instance, you can't attach a ref to a stateless function component. Normally this isn't an issue, since stateless functions do not provide an imperative API. Without an imperative API, there isn't much you could do with an instance anyway. However, if a user wants to find the DOM node of a stateless function component, they must wrap the component in a stateful component (eg. ES6 class component) and attach the ref to the stateful wrapper component.

Answer 1

后备实例是内存中代表节点的对象。这是通常存储状态等内容的地方。

因此，如果您有一个无状态组件，您将不会有一个支持实例，因为它完全是无状态的。

关于无状态组件的几点:

• 没有生命周期方法
• 没有引用