wretch/dist/bundle/middlewares/throttlingCache.min.mjs.map

A tiny wrapper built around fetch with an intuitive syntax.

{"version":3,"file":"throttlingCache.min.mjs","names":[],"sources":["../../../src/middlewares/throttlingCache.ts"],"sourcesContent":["import type { WretchOptions, ConfiguredMiddleware } from \"../types.js\"\n\n/* Types */\n\nexport type ThrottlingCacheSkipFunction = (url: string, opts: WretchOptions) => boolean\nexport type ThrottlingCacheKeyFunction = (url: string, opts: WretchOptions) => string\nexport type ThrottlingCacheClearFunction = (url: string, opts: WretchOptions) => boolean\nexport type ThrottlingCacheInvalidateFunction = (url: string, opts: WretchOptions) => string | RegExp | void\nexport type ThrottlingCacheConditionFunction = (response: WretchOptions) => boolean\nexport type ThrottlingCacheOptions = {\n  throttle?: number,\n  skip?: ThrottlingCacheSkipFunction,\n  key?: ThrottlingCacheKeyFunction,\n  clear?: ThrottlingCacheClearFunction,\n  invalidate?: ThrottlingCacheInvalidateFunction,\n  condition?: ThrottlingCacheConditionFunction,\n  flagResponseOnCacheHit?: string\n}\n\n/**\n * ## Throttling cache middleware\n *\n * #### A throttling cache which stores and serves server responses for a certain amount of time.\n *\n * **Options**\n *\n * - *throttle* `milliseconds`\n *\n * > the response will be stored for this amount of time before being deleted from the cache.\n *\n * - *skip* `(url, opts) => boolean`\n *\n * > If skip returns true, then the request is performed even if present in the cache.\n *\n * - *key* `(url, opts) => string`\n *\n * > Returns a key that is used to identify the request.\n *\n * - *clear* `(url, opts) => boolean`\n *\n * > Clears the cache if true.\n *\n * - *invalidate* `(url, opts) => string | RegExp | null`\n *\n * > Removes url(s) matching the string/RegExp from the cache.\n *\n * - *condition* `response => boolean`\n *\n * > If false then the response will not be added to the cache.\n *\n * - *flagResponseOnCacheHit* `string`\n *\n * > If set, a Response returned from the cache whill be flagged with a property name equal to this option.\n *\n */\nexport type ThrottlingCacheMiddleware = (options?: ThrottlingCacheOptions) => ConfiguredMiddleware & {\n  cacheResponse(key: any, response: any): void;\n  cache: Map<any, any>;\n  inflight: Map<any, any>;\n  throttling: Set<unknown>;\n}\n\n/* Defaults */\n\nconst defaultSkip = (_url, opts) => (\n  opts.skipCache || opts.method !== \"GET\"\n)\nconst defaultKey = (url, opts) => opts.method + \"@\" + url\nconst defaultClear = () => false\nconst defaultInvalidate = () => null\nconst defaultCondition = response => response.ok\n\nexport const throttlingCache: ThrottlingCacheMiddleware = ({\n  throttle = 1000,\n  skip = defaultSkip,\n  key = defaultKey,\n  clear = defaultClear,\n  invalidate = defaultInvalidate,\n  condition = defaultCondition,\n  flagResponseOnCacheHit = \"__cached\"\n} = {}) => {\n\n  const cache = new Map()\n  const inflight = new Map()\n  const throttling = new Set()\n\n  const throttleRequest = _key => {\n    if (throttle && !throttling.has(_key)) {\n      throttling.add(_key)\n      setTimeout(() => { throttling.delete(_key) }, throttle)\n    }\n  }\n\n  const middleware = next => (url, opts) => {\n    const _key = key(url, opts)\n\n    let invalidatePatterns = invalidate(url, opts)\n    if (invalidatePatterns) {\n      if (!(invalidatePatterns instanceof Array)) {\n        invalidatePatterns = [invalidatePatterns]\n      }\n      invalidatePatterns.forEach(pattern => {\n        if (typeof pattern === \"string\") {\n          cache.delete(pattern)\n        } else if (pattern instanceof RegExp) {\n          cache.forEach((_, key) => {\n            if (pattern.test(key)) {\n              cache.delete(key)\n            }\n          })\n        }\n      })\n    }\n    if (clear(url, opts)) {\n      cache.clear()\n    }\n\n    if (skip(url, opts)) {\n      return next(url, opts)\n    }\n\n    if (throttling.has(_key)) {\n      // If the cache contains a previous response and we are throttling, serve it and bypass the chain.\n      if (cache.has(_key)) {\n        const cachedClone = cache.get(_key).clone()\n        if (flagResponseOnCacheHit) {\n          // Flag the Response as cached\n          Object.defineProperty(cachedClone, flagResponseOnCacheHit, {\n            value: _key,\n            enumerable: false\n          })\n        }\n        return Promise.resolve(cachedClone)\n        // If the request in already in-flight, wait until it is resolved\n      } else if (inflight.has(_key)) {\n        return new Promise((resolve, reject) => {\n          inflight.get(_key).push([resolve, reject])\n        })\n      }\n    }\n\n    // Init. the pending promises Map\n    if (!inflight.has(_key))\n      inflight.set(_key, [])\n\n    // If we are not throttling, activate the throttle for X milliseconds\n    throttleRequest(_key)\n\n    // We call the next middleware in the chain.\n    return next(url, opts)\n      .then(response => {\n        // Add a cloned response to the cache\n        if (condition(response.clone())) {\n          cache.set(_key, response.clone())\n        }\n        // Resolve pending promises\n        inflight.get(_key).forEach(([resolve]) => resolve(response.clone()))\n        // Remove the inflight pending promises\n        inflight.delete(_key)\n        // Return the original response\n        return response\n      })\n      .catch(error => {\n        // Reject pending promises on error\n        inflight.get(_key).forEach(([, reject]) => reject(error))\n        inflight.delete(_key)\n        throw error\n      })\n  }\n\n  // Programmatically cache a response\n  middleware.cacheResponse = function (key, response) {\n    throttleRequest(key)\n    cache.set(key, response)\n  }\n  middleware.cache = cache\n  middleware.inflight = inflight\n  middleware.throttling = throttling\n\n  return 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