frontend-bootcamp/docs/step1-07/final/src/components/TodoFooter.tsx

import React from 'react';
import { Todos } from '../TodoApp.types';
interface TodoFooterProps {
  clear: () => void;
  todos: Todos;
}

export const TodoFooter = (props: TodoFooterProps) => {
  const itemCount = Object.keys(props.todos).filter(id => !props.todos[id].completed).length;
  const _onClick = () => {
    props.clear();
  };

  return (
    <footer>
      <span>
        {itemCount} item{itemCount > 1 ? 's' : ''} left
      </span>
      <button onClick={_onClick} className="submit">
        Clear Completed
      </button>
    </footer>
  );
};