React + TypeScript Syntax - Tasty Web Development Treats

In this episode of Syntax, Scott and Wes talk about using React with Typescript — how to set it up, components, state, props, passing data, custom hooks, and more!
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Show Notes 04:55 - Components
Strategies Example: type Props = { value: string; } const App = (props: Props) => div /> Return type? JSX.Element FC or FunctionComponent It’s discouraged for this reason: It means that all components accept children, even if they're not supposed to It could be useful for a return type 12:13 - Props
Default props: const defaultJoke: JokeProps = { joke: 'LOL JOE', id: 'YEAH', status: 200, }; function JokeItem({ joke = defaultJoke }: JokeProps): JSX.Element { return ( {joke.joke} = {joke.id} ); } Because props are always destructured, you often have to make a new type for your props. You can’t just type each argument by itself. 18:38 - State
Just like Generics, State can be inferred If your type is simple and you’re using useState, it just works:
const [user, setUser] = useState(null); 22:27 - useEffect
Nothing special required Good use of void: If you want to use a Promise function but not worry about await or .then(), you can pop a void in front of it: useEffect(() => { console.log('Mounted'); // getJoke().then(console.log).catch(console.error); void getJoke(); }, [getJoke]); 26:09 - Refs
Very similar to state however some interesting things with null:
const ref1 = useRef(null!); “Instantiating the ref with a current value of null but lying to TypeScript that it’s not null.” 29:33 - Custom Hooks
This is a great use case for Tuples 31:00 - Context
This is probably the most complex thing in this list First define the types Use generic to pass in types OR null This can also be non-null if you have default values in createContext:
const AppCtx = React.createContext(null); 35:21 - Events
The React events system is better than Vanilla JS Can handle them inline and have it inferred: onClick={e ⇒ yeah(e.target)} const onSetType = (e: React.ChangeEvent) => setType(e.target.value) React has a bunch of events built in — many of them take a Generic argument so you can specify the type of element that triggered it. Handy for native API methods like play and pause. 39:27 - ForwardRef
Again use of > to pass in forwarded ref type as param 1, Props types as param 2: type Props = { chi