Event that communicates if the scroll bar was available in the UI

Technical Support
1

Which product are you using?
PDF.js Express Viewer

Detailed description of issue
We have to make sure that the end user scrolls to the end of the document before they sign the document. We have been using the “scroll” event to see if the user has scrolled the document, but we just noticed that in some cases when the PDF is a single page PDF, the view on smaller screen sizes is not loading a scroll bar (it loads a scroll bar on web). Is there an event that will tell us if the scroll bar was rendered when the viewer loaded on the device? We can use this event to not do the scroll check on our end. If anyone has any other ideas/approaches on how to solve for this in general, please include them as well.

Expected behaviour
Event re scroll bar not loading in the UI

Does your issue happen with every document, or just one?
Only in mobile view/smaller screen sizes

Link to document
Not relevant

Code snippet
Current code - viewerContainer.addEventListener(‘scroll’, function() {
var s = $(viewerContainer).scrollTop();
var d = $(viewer).height();
var c = $(viewerContainer).height();
var scrollPercent = (s / (d - c)) * 100;
var event;
if(scrollPercent > 95){
event = new Event(‘scrolledToBottom’);
pdfViewer.dispatchEvent(event);
}

3

Hello Nate.barber,

Instead of checking for this, you could do something like:

const scrollView = instance.Core.documentViewer.getScrollViewElement()
scrollView.onscroll = () =>{   
  if (scrollView.offsetHeight + scrollView.scrollTop >= scrollView.scrollHeight) {
    console.log('bottom')
  }
 }