Intersection Observer not behaving as expected on Windows Insiders Preview build 14986

Issue #11299415 • Assigned to Christian F.


Ishaan N.
Mar 16, 2017
This issue is public.
Found in
  • Microsoft Edge
Reported by 1 person

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Steps to reproduce

Intersection observer has some inconsistencies that our team detected. We built a test page that uses Intersection observer to log the percentage of the red square viewable. At certain instances, even though 100% of the square is visible, it would log only 92% of it is visible. Upon zooming in and zooming out there are even more inconsistencies. When zooming out to 25%, the browser logs 0% of the square is in view, even though 100% of it is. Similarly, when zooming in, the browser logs that 99%-100% of the square is in view even though far less of it is in view. We double checked and none of these inconsistencies exist on chrome or on firefox’s version of a preview build.


Comments and activity

  • Microsoft Edge Team

    Changed Assigned To to “Steven K.”

  • Hi, I saw that the latest Windows 10 Creators update was released (build 1703) and Intersection Observer was formally released on it, with a blog post released by Microsoft on the same. I downloaded and did the same tests for Intersection Observer and found that the issues still exist. Would it be possible to get an update on this issue or a timeline on when it might get fixed by? Thanks.

  • Hi Ishaan,

    Would you be willing to provide your intersection_test.html or another repro?  A repro reduces the chance of us not seeing the same issue and reduces the time to triage.

    Appreciate the support,

    The MS Edge Team

  • Hi Steven,

    Sure, the test page I used was:

    It basically uses IntersectionObserver to log what percentage of the red square is viewable (you might have to scroll down a bit to find it initially) on all events such as scrolling, zooming etc. Let me know if you need anything else. Thanks!

  • Hi Ishaan,

    Thank you for the repro.  That helped.  I was able to repro this in the latest internal and insider fast builds.

    Appreciate the quick response and the support,

    The MS Edge Team

  • Microsoft Edge Team

    Changed Assigned To to “Balaji B.”

  • Hi Steven K., just wanted to follow up here. Will this be resolved in the next Edge release?

  • Microsoft Edge Team

    Changed Assigned To to “Christian F.”

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