I've been researching how to prevent Safari's feature of swiping at the edge of the screen to navigate to previous/next pages in browser history. I have an application that uses Hammer.js to pan an image, and on mobile the image takes up the whole screen. So if the user happens to start panning at the left edge of the image, for example, it forgoes that by ignoring my little javascript app and instead going to the previous page. I haven't found anything saying it is actually possible to prevent this edge swipe feature...though I did find this: https://gist.github.com/mountainstorm/9430618. However, all it seemed to accomplish for me was breaking mouse scroll functionality.
Any help would be greatly appreciated. Thanks!
I don't think it can be done since it is an OS level feature. As long as the swipes initiate inside the web page, there should not be any issue. If you have sufficient margin from the edge, then it should not be a problem.
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We're trying to build a chat view in React that behaves like WhatsApp or Telegram: First, it should show 20 initial chat messages, and if users scroll up, additional messages are being loaded.
To make this happen, we remember the position of the first message on top, load more messages before it, and then scroll back to that message to keep the scroll position where it was (and thus prevent the content from jumping).
This already works perfectly on Desktop and Android browsers. But when we try it out on Safari iOS, the browser behaves pretty weird. Sometimes it jumps to the wrong position, and sometimes the whole messages disappear. They will re-appear once you scroll the page again with your finger.
Does anyone know the reason for this strange behavior and/or a solution for this? We've been searching the web for months now.
(Bonus: Any hint to a working (!) React component that allows lazy loading of content on top of a list while pertaining scroll position reliably on iOS would be highly appreciated. We tried quite a number of them, but none worked.)
In iOS Safari these days, the user can trigger a system BACK or FORWARD by swiping from the far left or right of the screen.
What I'm wondering is if there's a way to detect this condition (from JavaScript), while it's happening (as well as after the history navigation has occurred). That is, distinguish it from a swipe that is not causing system behaviors, and distinguish the end navigation from one triggered by a back button.
I see that there may have been a hacky way to detect whether the navigation on iOS7 was triggered by swipe or not (based on a bug about missing the touchend), but I'm not sure that method works anymore in iOS 9+. Also, it doesn't tell me during the swipe what is going on (I ideally need to suppress my touchmove handlers while the System is doing its thing...).
http://jsbin.com/nesiside/1 (code is available http://jsbin.com/nesiside/1/edit)
If you scroll down in the document and click the "Lock/Unlock" button, an overlay with text will appear. You'll notice that the scrollbar length has been changed to accommodate the overlay height, not the original page height. Click "Unlock" in the overlay, and you return to the original page, in the previous scroll position.
System works great on desktop browsers, and on my Android phone, however, on iOS there is a rendering flash flash when the overlay is triggered or removed. Ultimately, I believe it is the fault of the scrollbar changing.
I've attempted the usual tricks to resolve iOS rendering issues (webkit-backface, transform3d), with no success.
Apparently, showing the content and hiding the overlay (or vise versa) was to much for the iPad 4 to render at once, causing the flash. This is odd because I tested it on an old Kindle and my Android phone and both are handled it fine with their slow processors.
To resolve the issue, I put the the scrollTop() method (used to return the user to the previous position on the underlying page) inside a requestAnimationFrame function. The result isn't perfect (content can be screen scrolling for a fraction of as section), but it is a much better result than an entire page flash.
This isn't a specific JS code issue, but more the way iOS deals with JS that is causing more problems on my site than most others.
On iOS only (it doesn't happen on Android) if I'm natively scrolling (up/down) and then try to activate some JS just before the scroll has finished (very quickly) then it completely ignores the JS.
I believe that Apple do this so that the UX always remains priority (don't let any crappy JS slow down the user), but in this case it's just a very simple piece of JS that I want to allow to run.
As an example, if a user is scrolling and then quickly presses a tab at the top of the screen that opens a fixed navigation panel then it won't register if the native scroll is still happening. If they press it again (the scroll has finished) then it works.
I'm also using a JS slider to scroll horizontally through images and if I try to scroll left/right just before the native up/down scroll has finished it sort of jumps and isn't good UX. I think it's prioritising the native scroll but still activating the horizontal scroll with some sort of delay.
It's not a massive problem, but not perfect. If everybody slowly navigated the site and waited for the native scroll to come to a complete stop, it would be great. But of course people won't do this.
I don't think preventing the default behaviour will do anything. I have tried to take over the native scroll before on iOS and I just don't think you can.
I think this may actually happen on many sites. I've just tried to find a good example by visiting stackoverflow.com on an iPhone and if you scroll quickly and then quickly hit a link before the scroll has finished it won't register. I don't think text links are as big a UX issue though, but a horizontal slider and big 'open menu' button at the top are much more likely to be hit quickly before the native scroll has ended (as you don't need to read something before you press it, like with text links).
I have various JS scripts on a site that would benefit from this being improved in iOS, so if I can understand a way around it, why it happens, what is going on, then I can apply individual fixes to each of those scripts.
Thanks.
The problem is not that iOS ignores javascript while scrolling (more precisely, while the scroll momentum is active). The problem is that, while that happens, iOS does not really register the position change of elements on the screen. In fact, if you have a handler attached to the scroll event, it will stop firing the moment you stop touching the screen, and then will fire just once when the scrolling stops.
Consequence? You think you're touching a link, but you aren't. The image on the screen has moved up or down, but, to the broswer, everything is on the same position, so, actually, you aren't touching anything (or are touching something different). I got very annoyed when I found this behaviour because, in my case, my page is full of images that are links to a gallery ... and if you touch them while scrolling, the gallery opens showing you not the image you touched, but another (The one that really was on that position when your fingers stopped touching the screen).
Is there a workaround? The only one that I know of is disabling the scroll momentum, but you lose scrolling performance.
I'm trying to build a menu with 5 blocks that the user can spin around.
You can see a demo here: http://m.iijax.com/menu.php
Works fine on iPhone, (if a little sluggish sometimes, but that is beside the point :p ) if i draw my finger more then 90 pixels (which i set as a limit) in either direction the menu spins.
On Android (2.1, a Samsung Galaxy S) however the menu does nothing until i release my finger from the screen, I've tried adding an alert on the 2 functions that changes a bunch of classes around to spin the menu either to the right or left and they do get triggered as I draw my finger.
So my best guess is either the browser locks access to the DOM until touchEnd, or it blatantly cheats and simply shows me some kind of screenshot of the page awaiting touchEnd.
Can anyone confirm either of these theories? I've spent about an hour searching here and on google and found nothing, but maybe I haven't found the rightsearch terms.
I've tried lots of swipe and slider examples I've found however and haven't found anything that animates in real time as i draw my finger.
Would also be interesting to know if this menu works on newer Android versions.