TYPESCRIPT

ts async function type

// async anonymous  function always returns a Promise
const dramaticWelcome: Promise<void> = async () => {
    console.log("Hello");

    for (let i = 0; i < 5; i++) {
        // await is converting Promise<number> into number
        const count: number = await delay(500, i);
        console.log(count);
    }

    console.log("World!");
}

type async function typescript

interface SearchFn {
    (subString: string): Promise<boolean>;
}
// or as a type declaration:
type SearchFn = (subString: string) => Promise<boolean>;