[wp-trac] [WordPress Trac] #46713: Comment reply link uses inconvenient eventlistener

[WordPress Trac]

#46713: Comment reply link uses inconvenient eventlistener
--------------------------+------------------------------
 Reporter:  szandman      |       Owner:  (none)
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  Awaiting Review
Component:  Comments      |     Version:  5.1
 Severity:  normal        |  Resolution:
 Keywords:                |     Focuses:
--------------------------+------------------------------

Comment (by janpaulkleijn):

 Hi there,
 During my efforts to make my website more accessible I was also pointed
 out by Google LightHouse that the adding of the 'touchstart' event
 listener in this file lacked the option **passive**.

 This can be corrected by altering the file: ''wp-includes/js/comment-
 reply.min.js''

 First the availability of support for the option parameter in the User
 Agent must be checked.
 https://developer.mozilla.org/en-
 US/docs/Web/API/EventTarget/addEventListener#Safely_detecting_option_support

 Check option support (minified)
 {{{
 var supportsPassive=false;try{var
 opts=Object.defineProperty({},'passive',{get:function(){supportsPassive=true;}});window.addEventListener("testPassive",
 null, opts);window.removeEventListener("testPassive", null, opts);} catch
 (e) {}
 }}}

 So you insert this code in the ''comment-reply.min.js'' file, right above
 the current code.

 Then the option must be added to the call for the 'touchstart' event
 listener in the code itself. Where you see:

 {{{
 addEventListener("touchstart",f)
 }}}

 you should replace it with:

 {{{
 addEventListener("touchstart",f,supportsPassive?{passive:true}:false)
 }}}

 At the moment this event listener is found only twice in the beginning
 part of the code.

 This will solve your issue.

 A good and thorough explanation of passive event listeners:
 https://github.com/WICG/EventListenerOptions/blob/gh-pages/explainer.md

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Ticket URL: <https://core.trac.wordpress.org/ticket/46713#comment:3>
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