react-query/lib/createWebStoragePersister/index.mjs

Hooks for managing, caching and syncing asynchronous and remote data in React

import { noop } from "../core/utils.mjs";
export function createWebStoragePersister({
  storage,
  key = "REACT_QUERY_OFFLINE_CACHE",
  throttleTime = 1000,
  serialize = JSON.stringify,
  deserialize = JSON.parse
}) {
  //try to save data to storage
  function trySave(persistedClient) {
    try {
      storage.setItem(key, serialize(persistedClient));
    } catch {
      return false;
    }

    return true;
  }

  if (typeof storage !== 'undefined') {
    return {
      persistClient: throttle(persistedClient => {
        if (trySave(persistedClient) !== true) {
          const mutations = [...persistedClient.clientState.mutations];
          const queries = [...persistedClient.clientState.queries];
          const client = { ...persistedClient,
            clientState: {
              mutations,
              queries
            }
          }; // sort queries by dataUpdatedAt (oldest first)

          const sortedQueries = [...queries].sort((a, b) => a.state.dataUpdatedAt - b.state.dataUpdatedAt); // clean old queries and try to save

          while (sortedQueries.length > 0) {
            const oldestData = sortedQueries.shift();
            client.clientState.queries = queries.filter(q => q !== oldestData);

            if (trySave(client)) {
              return; // save success
            }
          } // clean mutations and try to save


          while (mutations.shift()) {
            if (trySave(client)) {
              return; // save success
            }
          }
        }
      }, throttleTime),
      restoreClient: () => {
        const cacheString = storage.getItem(key);

        if (!cacheString) {
          return;
        }

        return deserialize(cacheString);
      },
      removeClient: () => {
        storage.removeItem(key);
      }
    };
  }

  return {
    persistClient: noop,
    restoreClient: noop,
    removeClient: noop
  };
}

function throttle(func, wait = 100) {
  let timer = null;
  let params;
  return function (...args) {
    params = args;

    if (timer === null) {
      timer = setTimeout(() => {
        func(...params);
        timer = null;
      }, wait);
    }
  };
}