Question

I am trying to detect when a user has finished scrolling a web page using Javascript on Android. The script I have is working on iPhone and seems correct to me that it should work on Android. Anyway, a snippet:

previous = pageYOffset;
interval = setInterval(function() {
    //Has scrolling stopped?
    if(previous == pageYOffset) {
        clearInterval(interval);
        //DO SOMETHING AFTER SCROLL COMPLETE
    } else {
        previous = pageYOffset;
    }
}, 200);

The basic idea, poll the pageYOffset every 200ms, if there had been no change then there is no scrolling happening. Otherwise, keep looking.

As I said, this works on iPhone, so I am assuming it is something to do with Android possibly not updating pageYOffset during a scroll?

Any help is greatly appreciated!

Note: I went for this route as I could not find a isScrolling property or scrollStop type event. If I have overlooked one, please do tell me 🙂

---

Update: Just tried to use the ‘scroll’
event to detect this. Mixed results
here. On the Android emulator it was
working almost correctly, but was very
intermittent on an actual phone (2.1
Sense Hero GSM), i.e. only 1 in 10
scrolls were detected.

Even when it was ‘working’ on the
emulator it was not firing the scroll
event when you scroll ‘up’ when you
are at the top of the page (i.e. to
push up to see the address bar). This
is a problem as the page has actually
been scrolled (changed position) but I
am not recieving the event.

Note, the iPhone does seem to fire and
detect the event correctly (at least
in the emulator, no access to device
at the moment).

Any ideas?

---

Update 2: The new ‘scroll’ event seems
to work (to the same extent as the
emulator (1.6 and 2.1)) on SOME
Android devices. Will continue to
investigate to try to narrow this
down.

Still the issue of ‘scroll’ not being
fired when you scroll up to the
address bar. Might have to have some
kind of hybrid solution of ‘scroll’
event detection and movement polling
after a touch.

Answer 1

The Hero helpfully interposes itself on occasional events and doesn’t report them correctly to javascript. We discovered a number of these in our Android development. Sometimes it seems to matter which way you are holding the phone (not kidding!)