process(pageList) {
    pageList.forEach(function (item) {
      this.pages.push(item.page);

      if (item.cfi) {
        this.locations.push(item.cfi);
      }
    }, this);
    this.firstPage = parseInt(this.pages[0]);
    this.lastPage = parseInt(this.pages[this.pages.length - 1]);
    this.totalPages = this.lastPage - this.firstPage;
  }
Process pageList items
@private
@param  {array} pageList