Method getHeader

js/src/index.ts:764–791

(source: Source)

  }

  async getHeader(source: Source): Promise<Header> {
    const cacheKey = source.getKey();
    const cacheValue = this.cache.get(cacheKey);
    if (cacheValue) {
      cacheValue.lastUsed = this.counter++;
      const data = await cacheValue.data;
      return data as Header;
    }

    const p = new Promise<Header>((resolve, reject) => {
      getHeaderAndRoot(source, this.decompress)
        .then((res) => {
          if (res[1]) {
            this.cache.set(res[1][0], {
              lastUsed: this.counter++,
              data: Promise.resolve(res[1][2]),
            });
          }
          resolve(res[0]);
          this.prune();
        })
        .catch((e) => {
          reject(e);
        });
    });
    this.cache.set(cacheKey, { lastUsed: this.counter++, data: p });
    return p;
  }

  async getDirectory(
    source: Source,