'paginationRange.length' is possibly 'undefined'.ts(18048)

I don't know how to get rid of this error 'paginationRange.length' is possibly 'undefined'.ts(18048)

export type IPaginate = {
    totalCount: number
    pageSize: number
    siblingCount: number
    currentPage: number
    onPageChange?: () => void
}

paginateHook.ts 👇

export const usePagination = ({totalCount, pageSize, siblingCount = 1, currentPage}: IPaginate) => {
    // do something here
}

UsePaginate.tsx 👇

const paginationRange = usePagination({
    currentPage,
    totalCount,
    siblingCount,
    pageSize
})

if ( currentPage === 0 || paginationRange?.length < 2){ // 'paginationRange.length' is possibly 'undefined'.ts(18048)
    return null
}

2 Replies

Jochem•2y ago

you're using the optional chaining operator (?.) to prevent an error like "cannot access property length of undefined", but I think you still can't compare undefined to 2 with < at least not in typescript you should probably be explicit about what you want to do if paginationRange is undefined, before you check if the length is less than 2. The compiler wants to know that it's safe to check the length of a variable that might be undefined, so it needs to be sure it isn't

Leke•2y ago

Thank you i have resolved it

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'paginationRange.length' is possibly 'undefined'.ts(18048)