Function getFetch

lib/adapters/fetch.js:618–639

(config)

const seedCache = new Map();

export const getFetch = (config) => {
  let env = (config && config.env) || {};
  const { fetch, Request, Response } = env;
  const seeds = [Request, Response, fetch];

  let len = seeds.length,
    i = len,
    seed,
    target,
    map = seedCache;

  while (i--) {
    seed = seeds[i];
    target = map.get(seed);

    target === undefined && map.set(seed, (target = i ? new Map() : factory(env)));

    map = target;
  }

  return target;
};

const adapter = getFetch();