update(react-hooks): global store hook (useStore)

issue #105

programming/web/reactjs/reactjsBasicNotes.md

@@ -470,6 +470,34 @@ function usePrevious(value) {
 }
 ```
 
+```js
+import { useState } from 'react';
+
+export const store = {
+  state: {},
+  setState(value) {
+    this.state = value;
+    this.setters.forEach(setter => setter(this.state));
+  },
+  setters: []
+};
+
+// Bind the setState function to the store object so
+// we don't lose context when calling it elsewhere
+store.setState = store.setState.bind(store);
+
+// this is the custom hook we'll call on components.
+export function useStore() {
+  const [ state, set ] = useState(store.state);
+
+  if (!store.setters.includes(set)) {
+    store.setters.push(set);
+  }
+
+  return [ state, store.setState ];
+}
+```
+
 ## ES6 Syntax
 
 ### this.setState()