react Context文档阅读

react/react文档.md

@@ -512,6 +512,39 @@ function tasksReducer(tasks, action) {
   }
 }
 ```
+## Context
+如果需要在先祖节点和子孙节点间隔多级时，从先祖节点向子孙节点传递数据，可以使用Context.  
+Context使用如下：
+### 创建Context
+```js
+import { createContext } from 'react';
+
+export const LevelContext = createContext(1);
+```
+### 子孙组件从Context中获取值
+```js
+import { useContext } from 'react';
+import { LevelContext } from './LevelContext.js';
+export default function Heading({ children }) {
+  const level = useContext(LevelContext);
+  // ...
+}
+```
+
+### 先祖节点提供Context
+```js
+import { LevelContext } from './LevelContext.js';
+
+export default function Section({ level, children }) {
+  return (
+    <section className="section">
+      <LevelContext.Provider value={level}>
+        {children}
+      </LevelContext.Provider>
+    </section>
+  );
+}
+```