For example we have the following code:
const TodoList = (props) => ( <div className="Todo-List"> <ul> {props.todos.map(todo => <TodoItem key={todo.id} {...todo} />)} </ul> </div> )
Because we wrote as function component, it is using the implicit return. To debug what props have been passed in. we can add console.log before the function:
const TodoList = (props) => console.log(props) || ( <div className="Todo-List"> <ul> {props.todos.map(todo => <TodoItem key={todo.id} {...todo} />)} </ul> </div> )
Because console.log return "underfined", so in the end, it will also run the function to render the statless component.