1028696 - m.welt.de jumps back to start of page with every scroll action

Status: RESOLVED WORKSFORME

(Web Compatibility :: Mobile, defect)

Description

[Stefan Fleiter (:sfleiter)]

What I did:

1. open m.welt.de on android
2. scroll down exactly once
   (touch with thumb and move it up once)
3. remember current position
4. scroll down again and watch screen

What happened:
* With the start of the second scroll movement the page
  jumps to the top before it starts scrolling.
* So if you try to scroll to the bottom of the page this is
  (nearly) impossible.
* The site is unusable because of this.

What I expected to happen:
* The second scroll movement should start from current position
  as on every other page.


welt.de is ranked 34 in Germany.

Works on:
 * Chrome for Android

Does not work:
 * Firefox for Android 30
 * Firefox for Android trunk (366b5c0c02d3)

If this is a Tech Evangelism bug 969842 and this one could probably be
communicated at once.

Comment 1

[Aaron Train [:aaronmt]]

I was able to reproduce this on trunk (Nightly 06.23) on my Nexus 5. CC'ing Web Compat.

Comment 2

[Kartikaya Gupta (email:[e-mail])]

As far as I can tell this is the web content calling scrollTo on touchdown.

Comment 3

[Hallvord R. M. Steen [:hallvors]]

Seems somebody is trying to work around a bug in specific webkit versions and happen to run the wrong code path in Firefox? This and the related code in script.end.min.js is the culprit:

    canBeFilledWithPoly = 'ontouchmove' in doc,
    overflowProbablyAlreadyWorks = 'WebkitOverflowScrolling' in docElem.style || (!canBeFilledWithPoly && w.screen.width > 1200) || (function () {
        var ua = w.navigator.userAgent,
        webkit = ua.match(/AppleWebKit\/([0-9]+)/),
        wkversion = webkit && webkit[1],
        wkLte534 = webkit && wkversion >= 534;
        return (ua.match(/Android ([0-9]+)/) && RegExp.$1 >= 3 && wkLte534 || ua.match(/ Version\/([0-9]+)/) && RegExp.$1 >= 0 && w.blackberry && wkLte534 || ua.indexOf(/PlayBook/) > - 1 && RegExp.$1 >= 0 && wkLte534 || ua.match(/Fennec\/([0-9]+)/) && RegExp.$1 >= 4 || ua.match(/wOSBrowser\/([0-9]+)/) && RegExp.$1 >= 233 && wkLte534 || ua.match(/NokiaBrowser\/([0-9\.]+)/) && parseFloat(RegExp.$1) === 7.3 && webkit && wkversion >= 533);
    }) (),

They should probably make sure overflowProbablyAlreadyWorks is also set to true in Firefox.

Comment 4

[Mike Taylor [:miketaylr]]

(In reply to Hallvord R. M. Steen from comment #3)
> Seems somebody is trying to work around a bug in specific webkit versions
> and happen to run the wrong code path in Firefox? This and the related code
> in script.end.min.js is the culprit:

Looks like that code originates from Overflow.js: https://github.com/scottjehl/Overthrow/blob/master/overthrow.js

Comment 5

[Kartikaya Gupta (email:[e-mail])]

Maybe they just need to update their UA matches? https://github.com/scottjehl/Overthrow/blob/master/overthrow.js#L42

Comment 6

[Stefan Fleiter (:sfleiter)]

This seems to be fixed by changes to the site and works now with Firefox for Android 30 and nightly.