javascript - in iOS8 using .focus() will show virtual keyboard and scroll page after touch

Question

Prior to iOS8, using the Javascript .focus() method on an input element would appear to have no effect (the virtual keyboard would not display). After the latest iOS 8 release, running the .focus() method seemed to have no effect on page load but once a user touched anywhere on the screen the virtual keyboard would instantly appear and scroll the page to the element in focus. (This is also an issue when I use the HTML attribute "autofocus")

This change has caused issues with iOS8 users on my site. When a user attempts to click a button on my page the sudden scroll and keyboard appearance causes them to unintentionally click a button that was lower on the screen.

I am assuming this is a bug in iOS8 and was not intentional feature, my question is what is the most efficient solution to fixing this problem?

Do I have to check navigator.userAgent to see if the device is iOS8, every time I use the .focus() method?

Answer 1

It looks like you're definitely hitting an iOS 8 bug. In iOS7, Safari would (apparently) ignore or keep unfocused elements that had focus set prior to page load. This includes both <input autofocus> and input.focus() that occur up to some point, possibly page load (I tested just with an inline script).

In iOS 8, Safari is now apparently remembering that the element was focussed but not actually focussing it until a touch down event. It is then blindly sending a click event to whichever element received the touch up.

Both browsers behave the same for input.focus() occurring after page load. They both zoom to the element and bring up the keyboard.

Tests:

• input.focus() before page load: http://fiddle.jshell.net/qo6ctnLz/3/show/
• <input autofocus>: http://fiddle.jshell.net/qo6ctnLz/4/show/
• input.focus() after page load: http://fiddle.jshell.net/qo6ctnLz/6/show/

The good news is that you only need to be worried about new behavior on elements you want to prefocus. The other good news is that while you will have to use a user-agent workaround, you can use it for all iOS versions since they were already behaving like you weren't autofocusing:

if (!/iPad|iPhone|iPod/g.test(navigator.userAgent)) {
    element.focus();
}

This appears to be the approach http://www.google.com uses based on some basic user-agent testing:

• Mac Book Pro: autofocus before page load.
• iPhone: no autofocus
• iPad: no autofocus
• Kit Kat (Android): focus after page load, possibly doing extra detection for presence of software keyboard.

If you haven't, you should go ahead and file a radar with Apple at https://bugreport.apple.com.