[wp-trac] [WordPress Trac] #57301: Emoji feature detection is incorrect

[WordPress Trac]

#57301: Emoji feature detection is incorrect
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 Reporter:  sergiomdgomes  |       Owner:  dmsnell
     Type:  defect (bug)   |      Status:  assigned
 Priority:  normal         |   Milestone:  6.2
Component:  Emoji          |     Version:  5.3
 Severity:  normal         |  Resolution:
 Keywords:                 |     Focuses:  javascript, performance
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Comment (by dmsnell):

 The easiest way to test this behavior will be to load a page in WordPress
 and then inspect `_wpemojiSettings` in the browser dev tools. The
 `supports` property will show whether the patch fixes the motivating bug.

  1. Start with a blank WordPress site.
  1. Set `define( SCRIPT_DEBUG, true )` in `wp-config` so that the source
 JS file is served instead of the minified one. Remove the `wp-includes/js
 /wp-emoji-loader.min.js` to ensure it won't be served.
  1. Load the home page for that site.
  1. Open the dev tools for your browser and inspect
 `_wpemojiSettings.supports`
  1. For modern browsers, `everything`, `flag`, and `emoji` should be
 false, and `twemoji.js` and `wp-emoji.js` scripts should load to provide
 support for the Emoji.
  1. Apply
 [https://core.trac.wordpress.org/attachment/ticket/57301/57301-3.diff
 57301-3.diff] and reload the browser.
  1. This time `everything`, `flag`, and `emoji` should be true, and
 neither of the two emoji support scripts should load.

 Looks like the attached pictures appeared inline so I won't copy them here
 into the instructions, but I have provided screenshots of tests in Safari,
 Firefox, and Chrome on macOS. Additionally I tested this on IE5 in Windows
 98 but before and after both reported no support for the Emoji, which
 isn't surprising because that support is missing. Still, the page did not
 crash, which is the more important aspect of testing.

 For mixed-support testing one needs to examine this on an OS that is old
 enough to lack more recent Unicode updates, but I don't think that part of
 the code has been under scrutiny or change, whereas the change is mostly
 isolated to fixing two things:
  - there was an outright bug in adding code points outside of the Basic
 Multilingual Plane which `fromCharCode` cannot properly translate
  - there was a change from storing these as numbers into storing these as
 text to try and simplify the indirect way these strings are created

 So all-in-all this is tested, confirmed, and safe. The only remaining
 questions are additional enhancements beyond the scope of this ticket,
 which are risks already present in WP that this patch does not also
 ameliorate (that being, preventing someone from adding new Emoji detection
 that breaks again).

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/57301#comment:28>
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