Comment by bussyfumes

Just had a script today that fires in 2 contexts and ran into an error where the element I attach a handler to doesn't exist in one of the contexts which breaks JS on the page. Since I already had jQuery as a dependency in the project, in the moment it felt easier to replace the querySelector call with jQuery, which I did, instead of checking the querySelect result so I second this, the 'fire and forget' part still holds up very well even though the tree traversal pain points have mostly been solved by browsers.