todo-list.component.ts

 handleModalTodoFormClose(response) {
    // is response an object?
    if (response === Object(response)) {
      if (response.createMode) {
        response.todo.id = response.id;
        this.todos.unshift(response.todo);
      } else {
        let index = this.todos.findIndex(value => value.id == response.id);
        this.todos[index] = response.todo;
      }
    }
}