Method $fetch

src/core/fetch/index.js:185–201

(cb = noop, $resetEvents = this.$resetEvents.bind(this))

    }

    $fetch(cb = noop, $resetEvents = this.$resetEvents.bind(this)) {
      const done = () => {
        this.callHook('doneEach');
        cb();
      };

      const onlyCover = this._fetchCover();

      if (onlyCover) {
        done();
      } else {
        this._fetch(() => {
          $resetEvents();
          done();
        });
      }
    }

    _fetchFallbackPage(path, qs, cb = noop) {
      const { requestHeaders, fallbackLanguages, loadSidebar } = this.config;