[wp-trac] [WordPress Trac] #31885: Widgets in Customizer fail to sync options in select[multiple]

[WordPress Trac]

#31885: Widgets in Customizer fail to sync options in select[multiple]
--------------------------+-----------------
 Reporter:  westonruter   |      Owner:
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  4.2
Component:  Customize     |    Version:  3.9
 Severity:  normal        |   Keywords:
  Focuses:  javascript    |
--------------------------+-----------------
 When a widget is updated in the Customizer, the form values are serialized
 and sent via Ajax to pass through the widget's update callback. The widget
 form with the sanitized values is then sent in the Ajax response. The form
 inputs in the Ajax response are then copied over from the response into
 the existing form. This sync logic, however, does not account for the
 special case of `select[multiple]` inputs which lack a single `value` to
 synchronize: the value to synchronize is an array of zero or more values.

 The issue with synchronizing the `selected` state among a
 `select[multiple] option` elements is particularly evident when the
 widget's underlying setting is changed programmatically, as opposed to
 direct user input. Here is a demonstration of the issue by using a widget
 undo/redo feature: https://cloudup.com/cuSHMWiSgdM

 Big props to [https://github.com/davidlonjon davidlonjon] for discovering
 this issue and suggesting a fix.

--
Ticket URL: <https://core.trac.wordpress.org/ticket/31885>
WordPress Trac <https://core.trac.wordpress.org/>
WordPress publishing platform