step 2.6 demo refinement

step2-06/demo/src/components/TodoFooter.tsx

@@ -0,0 +1,20 @@
+import React from 'react';
+import { DefaultButton, Stack, Text } from 'office-ui-fabric-react';
+import { actions } from '../actions';
+import { useMappedState, useDispatch } from 'redux-react-hook';
+
+export const TodoFooter = () => {
+  const { todos } = useMappedState(state => state);
+  const dispatch = useDispatch();
+
+  const itemCount = Object.keys(todos).filter(id => !todos[id].completed).length;
+
+  return (
+    <Stack horizontal horizontalAlign="space-between">
+      <Text>
+        {itemCount} item{itemCount === 1 ? '' : 's'} left
+      </Text>
+      <DefaultButton onClick={() => dispatch(actions.clear())}>Clear Completed</DefaultButton>
+    </Stack>
+  );
+};