If all you need is the CDN then simply add it after the </body>

function generatePDF() { const element = document.getElementById("pageprint"); document.getElementById("reportbox").style.display = "block"; document.getElementById("reportbox").style.marginTop = "0px"; document.getElementById("pageprint").style.border = "1px solid black"; html2pdf().from(element).save('download.pdf'); } function downloadCode(){ var x = document.getElementById("reportbox"); generatePDF(); setTimeout(function() { window.location=window.location;},3000);} <div> <div>Hello World!!</div> </div> <button type="button">Download HTML</button> <script src="https://cdnjs.cloudflare.com/ajax/libs/html2pdf.js/0.10.1/html2pdf.bundle.min.js" ></script>

However seems a very odd way to ask a user to download a pdf page since the option disappears after the download is attempted, so change of mind does not keep it user visible to try differently on fail.

So for example, I say open the download on current page, I see

but if I say open in PDF Viewer I see

It's much simpler to layout the printable HTML page as text not image, and suggest the user prints or saves exactly as their browser is configured and their desire, best result for all, especially as no libraries are needed. Nor will the page be cluttered by buttons.