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Opened 8 years ago

Closed 8 years ago

Last modified 7 years ago

#38021 closed enhancement (fixed)

Customize: remove support for IE8

Reported by: celloexpressions's profile celloexpressions Owned by: ryankienstra's profile ryankienstra
Milestone: 4.7 Priority: normal
Severity: normal Version:
Component: Customize Keywords: good-first-bug needs-patch
Focuses: Cc:


It is difficult to maintain support for Internet Explorer 8, and we typically no longer notice issues until close to or even after a release. The customizer already doesn't support IE7, or IE8 or 9 with domain mapping, so we can build on the no-customize-support class to actually make the customizer inaccessible on IE8.

The relevant code is in wp_customize_support() in wp-includes/theme.php. It uses feature detection in JS; we should add a check for something that isn't supported by IE8 but is supported by IE9 and other browsers. Ideally it should be something we've broken in IE8 in the customizer before.

Change History (19)

#1 @westonruter
8 years ago


This would allow us to start using the input event in #35832.

#3 @mrahmadawais
8 years ago

+1 about time!

This ticket was mentioned in Slack in #core-customize by celloexpressions. View the logs.

8 years ago

#6 @ryankienstra
8 years ago

Pull Request And Patch With Commit

This GitHub pull request and identical patch have a commit for this ticket:

Last edited 8 years ago by ryankienstra (previous) (diff)

#7 @ryankienstra
8 years ago

  • Keywords has-patch added; needs-patch removed

#8 @westonruter
8 years ago

Added some comments to

Not sure if the bits of code that exist to support IE8 should also be removed/deprecated.

#9 follow-up: @westonruter
8 years ago

In 38627:

Customize: Remove IE8 access to customizer to discontinue support.

Uses feature detection for Array.prototype.indexOf since it is not implemented in IE8.

Props ryankienstra.
See #38021.

#10 @westonruter
8 years ago

I've committed the initial patch to remove IE8 access. Now the question remains as to whether we should also remove code that was there for IE8, or if we should just remove that in the future as part of another ticket.

#11 in reply to: ↑ 9 @nacin
8 years ago

Replying to westonruter:

Uses feature detection for Array.prototype.indexOf since it is not implemented in IE8.

This could benefit from a code comment for sure.

I think it's fine to start stripping out IE8-specific code as part of this, just don't break anything. If it gets too complicated, then spin it off?

#12 @nacin
8 years ago

This could benefit from a code comment for sure.

I was just thinking something like "The customizer requires postMessage, CORS (if the site is cross domain), and IE8."

Would a shim to add support for Array.prototype.indexOf break this? That seems like it wouldn't be terribly uncommon. Since we don't control the environment on the frontend like we do in the dashboard, it may not be the best place for such feature detection.

#13 @westonruter
8 years ago

  • Owner set to ryankienstra
  • Status changed from new to assigned

@nacin Good points. Yes, a code comment would be good, and also it's true that a JS shim included via a plugin to add indexOf support would break the feature detection.

@ryankienstra Would you look at a more robust way to detect for IE8, including a code comment with the support detection, and also evaluate whether the IE8-supporting code can be easily removed in this ticket or if it should be done in another? Deprecation of the customize_preview_html5 method and removal of its hoo at wp_head seems like a choice at least.

#14 @westonruter
8 years ago

  • Keywords needs-patch added; has-patch removed

#15 @ryankienstra
8 years ago

Will Look For Other Feature-detection Solution

Hi @westonruter,
Sure, I'll look for another way to detect IE8. That's a good point that a shim or polyfill would break the feature detection with Array.prototype.indexOf.

#16 @ryankienstra
8 years ago

New Pull Request To Avoid Merge Conflics
Also Removes IE8 Workarounds

Development is now on a new pull request and identical patch, to avoid merge conflicts.

This also has commits to remove IE8 workarounds:

74482 : Customize - Deprecate function that's not needed without IE8 support.
Commit 2d583 removed Customizer support for IE8.
And this function is no longer needed.
So deprecate it, and remove the hook that calls it.

76ea6 : Customize - Remove IE8 polyfill in Selective Refresh.
The Customizer no longer supports IE8.

#17 @westonruter
8 years ago

  • Resolution set to fixed
  • Status changed from assigned to closed

In 38649:

Customize: Opt to disable IE8 support via conditional comments instead of using unreliable Array.prototype.indexOf feature detection.

Deprecate/remove WP_Customize_Manager::customize_preview_html5() and remove document.head polyfill, both of which were only in place for IE8 support.

Props ryankienstra, westonruter.
Fixes #38021.

This ticket was mentioned in Slack in #docs by afercia. View the logs.

8 years ago

This ticket was mentioned in Slack in #core-editor by afercia. View the logs.

7 years ago

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