ScrollView issues

[JayPanoz]

Just as a heads-up if you’re using the current master – or the jbks-shared branch…

There’s quite a significant amount of issues with the scroll view, that took an awful amount of time to debug because it’s not obvious – and there’s an off-by-one error courtesy of Safari iOS on top of that.

So the list of issues:

• chapters’ navigation bar (previous/next) not displayed when you reach the bottom of the current chapter;
• double-scroll happening in Chrome/Firefox i.e. you scroll and there’s an almost unnoticeable pause in your scrolling → that’s the iframe kinda behaving as a parasite, because its explicit height is not what those browsers expect;
• in addition, progression is not updated correctly in those browsers;
• finally onscroll event is not debounced (clear/setTimeout), so as resize, it will fire frantically – after debouncing it, I could see a significant performance boost in some browsers actually.

So to put it simply…

Don’t trust document.body when it comes to scroll. I learn the hard way scrolling is a clusterfuck, and document.body is supposed to be quirks mode.

In other words…

document.scrollingElement || document.body

is the way to go.

This scrollingElement will either be document.documentElement (compat mode) or document.body (quirks mode). And that pretty much solve all the issues, including in the iframe.