[wp-trac] [WordPress Trac] #25247: WP_Dependencies unsets a to do item when it isn't loaded

[WordPress Trac]

#25247: WP_Dependencies unsets a to do item when it isn't loaded
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 Reporter:  markoheijnen                         |       Owner:
     Type:  defect (bug)                         |      Status:  new
 Priority:  normal                               |   Milestone:  Future
Component:  Script Loader                        |  Release
 Severity:  normal                               |     Version:  3.6
 Keywords:  has-patch dev-feedback needs-        |  Resolution:
  testing                                        |     Focuses:
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Comment (by gitlost):

 I think the no src issue is a bit of a red herring. The real problem here
 is that the do_items() loop is removing an item from the to_do list
 whether or not it succeeded. An issue reported by helgatheviking on WP
 stackexchange
 ([http://wordpress.stackexchange.com/questions/168688/loading-a-script-
 with-a-dependency-is-unloading-another-scripts-dependency Loading a script
 with a dependency, is unloading another script's dependency] is another
 symptom of the problem, which can be seen simply with this setup:
 {{{
                 $scripts = new WP_Scripts;
                 $scripts->add( 'jquery-ui-datepicker', 'one', array(),
 'v1', 1 );
                 $scripts->add( 'wc-admin-meta-boxes', 'two', array(
 'jquery-ui-datepicker' ) );
                 $scripts->add( 'My_Plugin_Metabox', 'three', array( 'wc-
 admin-meta-boxes' ), 'v1', 1 );
                 $scripts->enqueue( array( 'My_Plugin_Metabox' ) );
                 $scripts->do_items( false, 0 );
                 $scripts->do_items( false, 1 );
 }}}
 Note the mismatch in groups between 'wc-admin-meta-boxes' and 'jquery-ui-
 datepicker', If you run this, 'jquery-ui-datepicker' won't be outputted,
 it's just appended to the $in_footer array in WP_Scripts and left there,
 and since the array is no longer used in do_footer_items(), it gets lost.

 Basically it seems that when the code was changed to do two passes of
 do_items() instead of one, the loop wasn't updated. The fix is simple,
 only remove the item from the to_do list when it's successfully added (or
 when the src is null).

 The helgatheviking scenario also shows up another issue, in that although
 with the loop fix 'jquery-ui-datepicker' will get outputted, it will
 output in the footer, after the dependent 'wc-admin-meta-boxes' which gets
 outputted in the head. To fix this it would seem best to force any
 dependencies to the lowest common group, which can I think be achieved by
 setting the class $this->group when recursing in set_group().

 I'll attach a patch and unit tests with these changes.

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Ticket URL: <https://core.trac.wordpress.org/ticket/25247#comment:11>
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