[wp-trac] [WordPress Trac] #44526: Admin Bar: Fail gracefully when adding events to non-existent elements

[WordPress Trac]

#44526: Admin Bar: Fail gracefully when adding events to non-existent elements
--------------------------+--------------------
 Reporter:  obenland      |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  low           |  Milestone:  5.0
Component:  Toolbar       |    Version:  3.1
 Severity:  minor         |   Keywords:
  Focuses:  javascript    |
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 When testing if `addEventListener` or `attachEvent` are available for an
 object it just checks for it to be truthy
 ([https://core.trac.wordpress.org/browser/trunk/src/js/_enqueues/lib
 /admin-bar.js?rev=43342#L302 source]), which works if it is available, if
 it's not it creates a type error:

 `TypeError: Cannot read property 'addEventListener' of null`

 This can occur in circumstances where jQuery is not available and
 plugin/themes remove nodes that `admin-bar.js` expects to be available. To
 reproduce install & activate [https://wordpress.org/plugins/logged-out-
 admin-bar/ Logged Out Admin Bar] and visit your test site with a theme
 enabled that does not use jQuery, like [https://wordpress.org/themes
 /responsive-kubrick/ Responsive Kubrick].

 While it's technically not a core bug, let's make sure it fails a little
 more gracefully when it does encounter these circumstances.

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Ticket URL: <https://core.trac.wordpress.org/ticket/44526>
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