function downloadPages(pageNo) {
for (var i=pageNo,n=pageNo + 9; i <= n; i++) {
const pageCanvas = document.getElementById('page_' + i);
if (pageCanvas === null) break;
const pageNo = i;
pageCanvas.toBlob(
blob => {
const anchor = document.createElement('a');
anchor.download = 'page_' + pageNo + '.png';
anchor.href = URL.createObjectURL(blob);
anchor.click();
URL.revokeObjectURL(anchor.href);
}
);
}
}downloadPages(1)
