Can't save Openlayers map as PDF

[Krukarius]

The implementation fo the following code:

https://openlayers.org/en/v3.20.1/examples/export-pdf.html

doesn't work

Under the following line:

              var pdf = new jsPDF('landscape', undefined, format);

console says, that

  Uncaught ReferenceError: jsPDF is not defined
   at e.<anonymous> (qgis2web.js:936)
   at e.r (events.js:50)
   at e.dispatchEvent (Target.js:115)
   at e.dispatchRenderEvent (Composite.js:76)
   at e.handlePostRender (PluggableMap.js:886)

After attaching the following scripts:

            <script src="https://unpkg.com/elm-pep"></script>
	<script src="https://cdn.polyfill.io/v2/polyfill.min.js? 
             features=fetch,requestAnimationFrame,Element.prototype.classList,URL"></script>
	  <script src="https://cdnjs.cloudflare.com/ajax/libs/jspdf/1.5.3/jspdf.min.js"></script>

The console says:

       Uncaught DOMException: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported.
     at e.<anonymous> 
      (file:///C:/Users/mariuszk/Desktop/Voneous/Interactive/Area%205%20V1%20Interactive/resources/qgis2web.js:938:19)
      at e.r (file:///C:/Users/mariuszk/Desktop/Voneous/Interactive/Area%205%20V1%20Interactive/resources/ol.js:1:24976)
       at e.dispatchEvent 
      (file:///C:/Users/mariuszk/Desktop/Voneous/Interactive/Area%205%20V1%20Interactive/resources/ol.js:1:27459)
      at e.dispatchRenderEvent 
      (file:///C:/Users/mariuszk/Desktop/Voneous/Interactive/Area%205%20V1%20Interactive/resources/ol.js:1:173800)
      at e.handlePostRender 
      (file:///C:/Users/mariuszk/Desktop/Voneous/Interactive/Area%205%20V1%20Interactive/resources/ol.js:1:113977)
       (anonymous) @ qgis2web.js:938
       r @ events.js:50
       e.dispatchEvent @ Target.js:115
       e.dispatchRenderEvent @ Composite.js:76

... and so on

The answer here:

https://stackoverflow.com/questions/31279582/openlayers-failed-to-execute-todataurl-on-htmlcanvaselement

says, that it must be the local proxy

I found another solution here:

https://www.reddit.com/r/learnprogramming/comments/7kxpdk/export_wms_layer_to_pdf_using_openlayers_and/

but it applies to PNG and JPEG.

How can I enable the PDF download (or at least PNG download) option for my openlayers map generated by QGIS2web plugin?