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

[WordPress Trac]

#57301: Emoji feature detection is incorrect
-------------------------------------+-----------------------------
 Reporter:  sergiomdgomes            |      Owner:  (none)
     Type:  defect (bug)             |     Status:  new
 Priority:  normal                   |  Milestone:  Awaiting Review
Component:  Emoji                    |    Version:  trunk
 Severity:  normal                   |   Keywords:
  Focuses:  javascript, performance  |
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 WP adds an inline script that performs feature detection for emoji support
 in the browser, the source for which is available at `wp-includes/js/wp-
 emoji-loader.js` [https://github.com/WordPress/WordPress/blob/master/wp-
 includes/js/wp-emoji-loader.js].

 This feature-detection is performed using a canvas that renders two
 different sequences and comparing them. The sequences are stored as arrays
 of hexadecimal numbers.

 Unfortunately, for a few revisions of this file now (more specifically
 since #45769), there have been mismatches introduced between the encoded
 format for the sequences and the way they're being decoded, in that the
 new sequences added have all been sequences of **code points**, but the
 decoding function (`emojiSetsRenderIdentically`) expects sequences of
 **char codes**.

 This causes every browser to fail the feature detection, even if it
 correctly supports the emoji features, and for the support polyfill to
 (unnecessarily) be loaded.

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Ticket URL: <https://core.trac.wordpress.org/ticket/57301>
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