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I recently had to implement a custom PDF viewer using PDF.js. It took a loooong time, because PDF.js is so confusing to work with. We went way over what we th

I recently had to implement a custom PDF viewer using PDF.js. It took a loooong time, because PDF.js is so confusing to work with. We went way over what we thought was a conservative time estimate. :( It's not just a matter of documentation, but API design. Beyond the bare minimum functionality, you'll need bits and pieces of semi-public API. For example, if you want to use the "text layer" (for selectable text) you'll need a CSS file which is inside the `web/` directory. But what's in `web/` is incomplete and not officially supported.

iapark 5y ago
I wish there were better wrappers for it too. One of the projects I'm still quite proud of that I made as a student was a react wrapper around PDF.js used here https://boardbook.kent.edu/ https://boardbook.kent.edu/ (though since they no longer seem to be using it I guess it will probably go dead at some point), but the fact there wasn't really a good open source one and as you say the docs were pretty lacking. My favorite discovery was that the performance was much worse unless I registered a particular scroll listener. It's been years now so I only vaguely remember, but I think registering a listener for `wheel` would cause scroll events to be treated as blocking and this made the whole scrolling experience less janky.