jQuery 3.1 includes changes that can affect attaching of behaviors by Drupal core drupal.js
The changes nicely described here:
https://github.com/jquery/jquery/issues/3271#issuecomment-320927335
Briefly, JS scripts with defer property cannot be executed because of poor internet connection for example.
The line
Drupal.attachBehaviors(document, Drupal.settings);
can be executed before loading of JS scripts with behaviors for some conditions.
I've faced with the issue at "heavy" sites with a lot of inernal, external JS scripts. I can't describe steps to reproduce here.
Proposed resolution described here https://developer.mozilla.org/en-US/docs/Web/API/Document/readyState
and possible patch for drupal.js can be the following or something like this:
document.onreadystatechange = function () {
if (document.readyState === "complete") {
Drupal.attachBehaviors(document, Drupal.settings);
}
}instead of
$(function () {
Drupal.attachBehaviors(document, Drupal.settings);
});
Discussion, implementation
https://github.com/jquery/jquery/issues/3271
https://developer.mozilla.org/en-US/docs/Web/API/Document/readyState
Needs review
7.0 ⚰️
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
We also encountered this issue on one of our sites. I opened a MR with a fix. Since jQuery doesn't seem to plan the fix anytime soon I think it makes sense to address this in Drupal core.