Modifying classList on a dynamically created <output> not yet added to the DOM prevents page rendering

By design Issue #7232103


Chuck R.
Apr 17, 2016
This issue is public.
Found in
  • Microsoft Edge
Found in build #
Reported by 2 people

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Steps to reproduce

Execute the following code in any page:
The message “This page is having a problem loading” is displayed rather than rendering the page.
OS X El Capitan Version 10.11.4
VirtualBox 5.0.16 r105871
Windows 10 Home Insider Preview
Version 1511
OS Build 14316.1000
Microsoft Edge 37.14316.1000.0
Microsoft EdgeHTML 14.14316
Here is a repro link for convenience:


Comments and activity

  • Microsoft Edge Team

    Changed Status to “By design”

  • Hello,

    This is an element that we have flagged as “Under Consideration” on our roadmap located here:

    You can add comments and vote on the feature here:–output-element

    Thanks for filing the feedback for us.

    All the best,
    The MS Edge Team

  • Hello,

    meanwhile output implementation shall be completed, but somehow you still cannot .classList on output-elements.

    In the first example ist just a simple output element, where a class is added with .className.

    and in this fiddle there is just added one javascript line output.classList.add('classlist'); but when try to open it in ie edge an error that there was a problem while page loading:

    Here is the error message in German:

    Beim Laden dieser Seite ist ein Problem aufgetreten.
    Wir haben ein paar Mal versucht, diese Seite zu laden, aber es gibt immer noch ein
    Problem mit der Website. Da Sie sicher wichtigere Dinge zu tun haben, als das Laden
    dieser Seite zu beobachten, empfehlen wir Ihnen, etwas später zu dieser Seite
  • Microsoft Edge 38.14393.0.0
    Microsoft EdgeHTML 14.14393

    I just saw, that I use another version of edge

  • Microsoft Edge 38.14393.0.0
    Microsoft EdgeHTML 14.14393

    Simplest way to reproduce: document.createElement('output').classList;

  • This seems to be fixed on Microsoft Edge 40.15063.0.0, Microsoft EdgeHTML 15.15063.

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