serwist/src/PrecacheRoute.ts

A Swiss Army knife for service workers.

/*
  Copyright 2020 Google LLC

  Use of this source code is governed by an MIT-style
  license that can be found in the LICENSE file or at
  https://opensource.org/licenses/MIT.
*/

import { Route } from "./Route.js";
import type { Serwist } from "./Serwist.js";
import type { RouteMatchCallback, RouteMatchCallbackOptions } from "./types.js";
import type { PrecacheRouteOptions } from "./types.js";
import { generateURLVariations } from "./utils/generateURLVariations.js";
import { getFriendlyURL } from "./utils/getFriendlyURL.js";
import { logger } from "./utils/logger.js";

/**
 * A subclass of {@linkcode Route} that takes a {@linkcode Serwist} instance and uses it to match
 * incoming requests and handle fetching responses from the precache.
 */
export class PrecacheRoute extends Route {
  /**
   * @param serwist A {@linkcode Serwist} instance.
   * @param options Options to control how requests are matched
   * against the list of precached URLs.
   */
  constructor(serwist: Serwist, options?: PrecacheRouteOptions) {
    const match: RouteMatchCallback = ({ request }: RouteMatchCallbackOptions) => {
      const urlsToCacheKeys = serwist.getUrlsToPrecacheKeys();
      for (const possibleURL of generateURLVariations(request.url, options)) {
        const cacheKey = urlsToCacheKeys.get(possibleURL);
        if (cacheKey) {
          const integrity = serwist.getIntegrityForPrecacheKey(cacheKey);
          return { cacheKey, integrity };
        }
      }
      if (process.env.NODE_ENV !== "production") {
        logger.debug(`Precaching did not find a match for ${getFriendlyURL(request.url)}.`);
      }
      return;
    };

    super(match, serwist.precacheStrategy);
  }
}