英文:
How does react re create react element tree (virtual DOM) on every state update?
问题
我已经阅读了关于每次状态更新时React生成React元素树（虚拟DOM）并使用差异算法将新生成的React元素树（虚拟DOM）与新的元素树进行比较的内容。但是这里有一个困惑。
假设我有一个组件树：
React组件树
如果在组件D中更新状态，那么React如何在不调用树中的所有组件的情况下创建整个新的React元素树（虚拟DOM）？
或者React只为更新的组件创建虚拟元素树，或者实际上发生了什么？
我阅读了很多关于React渲染行为的文章，但是无法弄清楚这一点。
英文:
I have been reading that for every state update react generates the react element tree (virtal dom) and compares the newly generated react element tree( virual dom) with the new one using a diffing algorithm. But here is the confusion.
suppose I have a tree of component
React component tree
And if the state is updated in component D, then how does react creates the whole new react element tree (virtual dom) without calling all the components in the tree?
Or does react just creates the virtual element tree for the updated component or what actually happens?
I read a lot of articles about react rendering behavior but couldn't figure out this.
答案1
得分: 0
假设你有一个组件树：A -> B -> C -> D
如果状态在组件D中更新，React将重新渲染组件D。
当组件D重新渲染时，React会为D生成一个新的虚拟DOM表示。
然后，React在先前的D虚拟DOM和新的D虚拟DOM之间执行差异化处理。
差异化处理过程识别出组件D虚拟DOM中发生的具体更改。
关键要理解的是，React的差异化算法通过仅关注受状态更改影响的组件来优化该过程。它不会触发与组件树中无关的部分的渲染。
因此，React不会为每次更新重新创建整个虚拟DOM或重新渲染整个组件树。它只选择性地更新由于状态更新而发生更改的虚拟DOM的部分。
这就是使React高效的原因，使其能够在复杂应用程序中提供流畅的用户体验。差异化算法能够识别和应用仅必要的更改，从而减少不必要的工作和DOM操作，实现更快、更高效的渲染。
英文:
Suppose you have a component tree: A -> B -> C -> D
If the state is updated in component D, React will re-render component D.
When component D is re-rendered, React generates a new Virtual DOM representation for D.
React then performs the diffing process between the previous Virtual DOM for D and the new one.
The diffing process identifies the specific changes that occurred in component D's Virtual DOM.
The crucial point to understand is that React's diffing algorithm optimizes the process by focusing only on the components that are affected by the state change. It doesn't trigger rendering for unrelated parts of the component tree.
So, React doesn't re-create the entire Virtual DOM or re-render the entire component tree for every update. It selectively updates only the parts of the Virtual DOM that have changed due to state updates.
This is what makes React efficient and enables it to provide a smooth user experience even in complex applications. The diffing algorithm's ability to identify and apply only the necessary changes reduces unnecessary work and DOM manipulation, resulting in faster and more efficient rendering.
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