jviall

Advanced TypeScript Techniques

Team Disco

• Dylan Roberts
• James Viall

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Topic: Generics

Types that take parameters

Typing the useState React hook

jviall

export function useAsyncDebounce<T extends (args: any[]) => any>(defaultFn: T, defaultWait: number): T {
    const debounceRef = React.useRef<{
        promise?: Promise<T>,
        resolve?: (value: T | PromiseLike<T>) => void,
        reject?: (reason?: any) => void,
        timeout?: NodeJS.Timeout
    }>({})

    // the given args could be props, which change, so we want to always use latest definitions.
    const getDefaultFn = useGetLatest(defaultFn)