[wp-trac] [WordPress Trac] #51171: Properly deprecate removed JavaScript globals

[WordPress Trac]

#51171: Properly deprecate removed JavaScript globals
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 Reporter:  joostdevalk   |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  5.5.2
Component:  General       |    Version:
 Severity:  normal        |   Keywords:
  Focuses:                |
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 In WordPress 5.5 the following global JavaScript objects
 [https://make.wordpress.org/core/2020/08/05/more-support-for-javascript-
 i18n-in-wordpress-5-5/ were removed] without being deprecated:

 * `wp.updates.l10n`
 * `wpPointerL10n`
 * `commonl10n`
 * `userProfileL10n`
 * `privacyToolsL10n`
 * `authcheckL10n`
 * `wp.themePluginEditor.l10n`
 * `tagsl10n`
 * `adminCommentsL10n`
 * `tagsSuggestL10n`
 * `wpColorPickerL10n`
 * `attachMediaBoxL10n`
 * `postL10n`
 * `inlineEditL10n`
 * `plugininstallL10n`
 * `navMenuL10n`
 * `commentL10n`
 * `setPostThumbnailL10n`

 This means that referencing these objects will now result in a JavaScript
 error and will thus halt JavaScript execution.

 Some of these objects were being used in very popular plugins. @omarreiss
 and I have been researching where these were used. This
 [https://docs.google.com/spreadsheets/d/1Vho7hJR4DMRyns38xcUMvVUj8SBov_J8_X4a7zwpmzo/edit?usp=sharing
 Google sheet] shows the impact.

 If we only count plugins with more than 100k installs or more, some of
 these already have an incredible impact. We should patch this as soon as
 possible. Our proposal is to make them fail silently: return an empty
 string and throw a console warning. This makes sure that JavaScript
 doesn't break, and also makes clear to plugin developers that they need to
 adapt.

 For the globals that are removed entirely, we can do the deprecation in
 common.js. For the globals that were properties on another global, we have
 to do the deprecation in the file that holds the parent global.

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Ticket URL: <https://core.trac.wordpress.org/ticket/51171>
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