create-fetcher

create-fetcher is a remote data fetching library, providing common features - configurable caching, retry, polling with both promised-based API and react hooks.

Install

npm i --save create-fetcher

Why fetcher?

create-fetcher is built around the standard fetch(), the goal of this library is not trying to replace fetch(), but to provide common utilities around the remote data fetching:

• configurable caching strategies: cache mode and maxAge, minFresh
• configurable cache stores: memory cache, local storage cache, async storage cache(react-native) or any custom cache stores that implement the Cache interface
• retry on failure
• polling (can be used together with retry on failure)
• request concurrency control: if a fetch request was triggered before another same request(share the same cacheKey) finished, they will be merged together, once 1 actual fetch request.
• built-in React hooks integration support: useSWR(), usePolling(), usePaginationList()

Basic concepts and quick start example

• fetcher: object instance that responsible for making fetch calls, the reason it is need to be a object is for concurrency control

// quick start
import { useSWR } from 'create-fetcher/lib/hooks';

function MyComponent1() {
    // send request by useSWR
    const { data } = useSWR('https://jsonplaceholder.typicode.com/todos/1');
    return (<div>{JSON.stringify(data)}</div>);
}


// create the fetcher instance to gain more control on cache and fetcher options
import { createFetcher } from 'create-fetcher';
import { useSWR } from 'create-fetcher/lib/hooks';

// create the fetcher instance, pass signal to fetch so it supports fully abort() the request
// otherwise calling abort() on `fetcher.fetch()` returns only aborts at application side (ignores request result).
const userInfoFetcher = createFetcher((id, { signal }) => fetch(`/api/v1/users/${id}`, { signal }), { cacheMaxAge: 7200 });

function MyComponent2() {
    // send request by useSWR with 1 as the id, and get the fetch result
    const { data } = useSWR(userInfoFetcher, 1);
    return (<div>{JSON.stringify(data)}</div>);
}

Usage

Please check out example project(react) for a usage demo.

API List (please use the TypeScript docs for more details)

• createFetcher(url, options): create a fetcher instance
• createFetcher(requestCreator, options): create a fetcher instance

React Hooks (lib/hooks)

• useSWR(url, request, options), useSWR(fetcher, request, options): basic request hook that supports caching, retry on failure
• usePolling(url, pollingWaitTime, request, options), usePolling(fetcher, pollingWaitTime, request, options): polling request hook
• usePaginationList(fetcher, dataHandler, initialRequest, options): for making pagination list request calls and merges the results into a single list
• useDeepEqualMemo(value), useShallowEqualMemo(value): for keep using previous value instance if new value equals with previous value

Caches (lib/caches)

• createMemoryCache(): in-memory cache
• createLocalStorageCache(keyPrefix, useMemoryCache): use localStorage as cache store
• createAsyncStorageCache(keyPrefix, useMemoryCache): for react-native, use AsyncStorage as cache store

Utilities to work with plain fetcher object

• forEachResponse(requestReturn, handler): callback for each request response, including response retrived from cache
• getFinalResponse(requestReturn): get the final response
• getInitialResponse(requestReturn): get thee first valid response, including response retrived from cache
• fallbackToPureFetch(fetcher): turn fetcher into a pure fetch function
• clearCache(cache, maxAge): clear expired items from cache