set up demo, exercise, final folders

step1-06/demo/src/components/TodoList.tsx

@@ -0,0 +1,20 @@
+import React from 'react';
+import { TodoListItem } from './TodoListItem';
+
+export class TodoList extends React.Component<any, any> {
+  render() {
+    const { filter, todos } = this.props;
+
+    const filteredTodos = Object.keys(todos).filter(id => {
+      return filter === 'all' || (filter === 'completed' && todos[id].completed) || (filter === 'active' && !todos[id].completed);
+    });
+    return (
+      <ul className="todos">
+        <TodoListItem />
+        <TodoListItem />
+        <TodoListItem />
+        <TodoListItem />
+      </ul>
+    );
+  }
+}