React和TypeScript-组件<Props & {}>

Question

What does this piece of code mean?

export class App extends Component<Props & { some: string; some2: string; }>

I mean... what is after the & sign

& { some: string; some2: string; }

Answer 1

It's an intersection type. When defining interfaces in typescript you can separate each property with a semicolon. You can also use commas. It doesn't matter.

https://www.typescriptlang.org/docs/handbook/interfaces.html

Answer 2

export class App extends Component<Props & { some: string; some2: string; }>

Is no different from

interface SomeInterface {
    some: string;
    some2: string;
}
export class App extends Component<Props & SomeInterface>

It's just written inline instead of creating a new interface for that one line.