example.md

In Drupal 9.4, jQuery.once() has been removed. However, there's a Javascript function, once(), that can replace it with a little rewriting:

var closeButton = $("#off-canvas .offcanvas__close");
      
closeButton.once().on("click", function () {
  closeOffCanvas();
});

once takes 3 arguments: 1. Arbitrary key, 2. CSS selector, 3. context
It looks like passing a jQuery object as the CSS selector works too 🤷🏽‍♀️

var closeButton = $("#off-canvas .offcanvas__close");

$(once("closeButton", closeButton, context)).on("click", function () {
  closeOffCanvas();
});

$("iframe").once().fitVids({
  customSelector: ['iframe[src*="youtu.be"]'],
});

$(once("iframe", "iframe", context)).fitVids({
  customSelector: ['iframe[src*="youtu.be"]'],
});