Also check element.sticky in onScrollEvents

[marcveens]

There is a possibility the sticky is destroyed while the scroll event is active. This could cause a "Cannot read property 'active' of undefined"

[analog-nico]

This is occurring very rarely in my production system, too. I would highly appreciate this to be merged.

A similar check would make sense for the onResizeEvents(...) function, too. But it’s probably too rare. I did not experience the same issue for this event yet. Just in case:

  onResizeEvents(element) {
+
+     if (!element.sticky) {
+         return;
+     }
+
      this.vp = this.getViewportSize();

[analog-nico]

Technically, element.sticky can only be falsy in case of the race condition as mentioned in the initial message for this PR. I reviewed the whole library code to verify that the component lifecycle is sound. All looks good to me!

[analog-nico]

FYI, here is a monkey patch that I am using now:

var Sticky = require('sticky-js');

var origOnScrollEvents = Sticky.prototype.onScrollEvents;
Sticky.prototype.onScrollEvents = function (element) {
    if (element.sticky) {
        origOnScrollEvents.call(this, element);
    }
};
var origOnResizeEvents = Sticky.prototype.onResizeEvents;
Sticky.prototype.onResizeEvents = function (element) {
    if (element.sticky) {
        origOnResizeEvents.call(this, element);
    }
};

// Any new Sticky(...) calls after the above