[wp-trac] [WordPress Trac] #34049: Emoji detection is broken on FF41, OS X 10.10

[WordPress Trac]

#34049: Emoji detection is broken on FF41, OS X 10.10
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 Reporter:  rmccue        |       Owner:
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  Awaiting Review
Component:  General       |     Version:
 Severity:  normal        |  Resolution:
 Keywords:                |     Focuses:
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Comment (by azaozz):

 I've tried a different detection approach:
 - Add 2 `<span style="font-size: 200px;">`, one with a "box" character (a
 valid char that the browser cannot render) and the other with an emoji.
 The spans should be off-screen, `position: absolute; left -1000em;` or
 similar.
 - Check the spans widths. If equal, there's no emoji support.

 This seems to work well (apart from being dependent on the emoji font
 having different width for the "box" char). However it has a major flaw:
 these spans have to be in the body for the browser to render them so we
 can get the width.

 Because of that the emoji detection script cannot run in the head, which
 is very desirable. There is a workaround: run in the head, append a fake
 body with the 2 spans, then remove it, however that is too hacky to add to
 all WordPress sites.

 Wondering if there is a way to "combine" the two methods.

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Ticket URL: <https://core.trac.wordpress.org/ticket/34049#comment:6>
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