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setState #101

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Lawguancong opened this issue Oct 12, 2021 · 0 comments

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Lawguancong commented Oct 12, 2021 •

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流程

首先，setState 会产生当前更新的优先级（老版本用 expirationTime ，新版本用 lane ）。
接下来 React 会从 fiber Root 根部 fiber 向下调和子节点，调和阶段将对比发生更新的地方，更新对比 expirationTime ，找到发生更新的组件，合并 state，然后触发 render 函数，得到新的 UI 视图层，完成 render 阶段。
接下来到 commit 阶段，commit 阶段，替换真实 DOM ，完成此次更新流程。
接下来会执行 setState 中 callback 函数,如上的()=>{ console.log(this.state.number) }，到此为止完成了一次 setState 全过程。

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