constructor(packageDocument) {
    this.manifest = {};
    this.navPath = '';
    this.ncxPath = '';
    this.coverPath = '';
    this.spineNodeIndex = 0;
    this.spine = [];
    this.metadata = {};

    if (packageDocument) {
      this.parse(packageDocument);
    }
  }
Open Packaging Format Parser
@class
@param {document} packageDocument OPF XML