How to use the jszip/dist/jszip.min function in jszip

public _$download() {
        let zip = new JSZip();
        const base64Codes = this._getGraphBase64Codes();
        base64Codes.forEach(base64Code => {
            zip.file(`${base64Code.title}.png`, base64Code.base64, {base64: true});
        });
        const jigsawGraphDownloadExportFileName = !!this.initData.jigsawGraphDownloadExportFileName.match(/(.+)\.(.+)/g) ?
            this.initData.jigsawGraphDownloadExportFileName : `${this.initData.jigsawGraphDownloadExportFileName}.zip`;
        zip.generateAsync({type: "blob"}).then(content => {
            FileSaver.saveAs(content, `${jigsawGraphDownloadExportFileName}`);
        });
    }
}