TypeScript React.FC<Props> confusion

I am learning TypeScript and some bits are confusing to me. One bit is below:

interface Props {
  name: string;
}

const PrintName: React.FC<Props> = (props) => {
  return (
    <div>
      <p style={{ fontWeight: props.priority ? "bold" : "normal" }}>
        {props.name}
      </p>
    </div>
  )
}

const PrintName2 = (props: Props) => {
  return (
    <div>
      <p style={{ fontWeight: props.priority ? "bold" : "normal" }}>
        {props.name}
      </p>
    </div>
  )
}

For both functional components above, I see TypeScript generates the same JS code. The PrintName2 component seems more streamlined to me as far as readability. I wonder what's the difference between the two definitions and if anyone is using second type of React component?

Solution 1:

Thanks all for the answers. They are correct but I was looking for a more detailed version. I did some more research and found this on React+TypeScript Cheatsheets on GitHub.

Function Components
These can be written as normal functions that take a props argument and return a JSX element.

type AppProps = { message: string }; /* could also use interface */

const App = ({ message }: AppProps) => <div>{message}</div>;

What about React.FC/React.FunctionComponent? You can also write components with React.FunctionComponent (or the shorthand React.FC):

const App: React.FC<{ message: string }> = ({ message }) => (
  <div>{message}</div>
);

Some differences from the "normal function" version:

It provides typechecking and autocomplete for static properties like displayName, propTypes, and defaultProps - However, there are currently known issues using defaultProps with React.FunctionComponent. See this issue for details - scroll down to our defaultProps section for typing recommendations there.

It provides an implicit definition of children (see below) - however there are some issues with the implicit children type (e.g. DefinitelyTyped#33006), and it might be considered a better style to be explicit about components that consume children, anyway.

const Title: React.FunctionComponent<{ title: string }> = ({
  children,
  title
}) => <div title={title}>{children}</div>;

In the future, it may automatically mark props as readonly, though that's a moot point if the props object is destructured in the parameter list.

React.FunctionComponent is explicit about the return type, while the normal function version is implicit (or else needs additional annotation).

In most cases, it makes very little difference which syntax is used, but the React.FC syntax is slightly more verbose without providing clear advantage, so precedence was given to the "normal function" syntax.

Solution 2:

React.FC is not the preferable way to type a React component, here's a link.

I personally use this type:

const Component1 = ({ prop1, prop2 }): JSX.Element => { /*...*/ }

Short list of React.FC cons:

1. Provides an implicit definition of children, even if your component doesn't need to have children. That might cause an error.
2. Doesn't support generics.
3. Doesn't work correctly with defaultProps.