React :传递条件渲染数据

function MyComponent(props) {
  if (props.isLoggedIn) {
    return <div>Welcome, {props.username}!</div>;
  } else {
    return <div>Please log in.</div>;
  }
}

function MyComponent(props) {
  return (
    <div>
      {props.isLoggedIn && <div>Welcome, {props.username}!</div>}
      {!props.isLoggedIn && <div>Please log in.</div>}
    </div>
  );
}

function MyComponent(props) {
  return (
    <div>
      {props.isLoggedIn ? (
        <div>Welcome, {props.username}!</div>
      ) : (
        <div>Please log in.</div>
      )}
    </div>
  );
}