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happy-dom breaking changes

Every breaking API change we have recorded in happy-dom on npm: 13,444 breaking changes in 30 versions. Below are its newest 6 versions, removals and renames first, each with its source.

Newest change October 20, 2026

On this page

21.0.4

429 breaking changes, first published October 20, 2026.

  • Removed AbortController.__@window@3465511
    AbortController.__@window@3465511 was removed in happy-dom 21.0.4 npmjs.com
  • Removed AbortSignal.__@aborted@3465527
    AbortSignal.__@aborted@3465527 was removed in happy-dom 21.0.4 npmjs.com
  • Removed AbortSignal.__@reason@3465529
    AbortSignal.__@reason@3465529 was removed in happy-dom 21.0.4 npmjs.com
  • Removed Animation.__@propertyEventListeners@3465587
    Animation.__@propertyEventListeners@3465587 was removed in happy-dom 21.0.4 npmjs.com
  • Removed Attr.__@affectsCache@3465736
    Attr.__@affectsCache@3465736 was removed in happy-dom 21.0.4 npmjs.com
  • Removed Attr.__@assignedToSlot@3465732
    Attr.__@assignedToSlot@3465732 was removed in happy-dom 21.0.4 npmjs.com
  • Removed Attr.__@cache@3465734
    Attr.__@cache@3465734 was removed in happy-dom 21.0.4 npmjs.com
  • Removed Attr.__@childNodes@3465730
    Attr.__@childNodes@3465730 was removed in happy-dom 21.0.4 npmjs.com
  • Removed Attr.__@clearCache@3465757
    Attr.__@clearCache@3465757 was removed in happy-dom 21.0.4 npmjs.com
  • Removed Attr.__@connectedToDocument@3465763
    Attr.__@connectedToDocument@3465763 was removed in happy-dom 21.0.4 npmjs.com

And 419 more in this version.

21.0.3

427 breaking changes, first published October 15, 2026.

  • Removed AbortController.__@window@3482173
    AbortController.__@window@3482173 was removed in happy-dom 21.0.3 npmjs.com
  • Removed AbortSignal.__@aborted@3482189
    AbortSignal.__@aborted@3482189 was removed in happy-dom 21.0.3 npmjs.com
  • Removed AbortSignal.__@reason@3482191
    AbortSignal.__@reason@3482191 was removed in happy-dom 21.0.3 npmjs.com
  • Removed Animation.__@propertyEventListeners@3482249
    Animation.__@propertyEventListeners@3482249 was removed in happy-dom 21.0.3 npmjs.com
  • Removed Attr.__@affectsCache@3482398
    Attr.__@affectsCache@3482398 was removed in happy-dom 21.0.3 npmjs.com
  • Removed Attr.__@assignedToSlot@3482394
    Attr.__@assignedToSlot@3482394 was removed in happy-dom 21.0.3 npmjs.com
  • Removed Attr.__@cache@3482396
    Attr.__@cache@3482396 was removed in happy-dom 21.0.3 npmjs.com
  • Removed Attr.__@childNodes@3482392
    Attr.__@childNodes@3482392 was removed in happy-dom 21.0.3 npmjs.com
  • Removed Attr.__@clearCache@3482419
    Attr.__@clearCache@3482419 was removed in happy-dom 21.0.3 npmjs.com
  • Removed Attr.__@connectedToDocument@3482425
    Attr.__@connectedToDocument@3482425 was removed in happy-dom 21.0.3 npmjs.com

And 417 more in this version.

21.0.2

426 breaking changes, first published October 15, 2026.

  • Removed AbortController.__@window@3498819
    AbortController.__@window@3498819 was removed in happy-dom 21.0.2 npmjs.com
  • Removed AbortSignal.__@aborted@3498835
    AbortSignal.__@aborted@3498835 was removed in happy-dom 21.0.2 npmjs.com
  • Removed AbortSignal.__@reason@3498837
    AbortSignal.__@reason@3498837 was removed in happy-dom 21.0.2 npmjs.com
  • Removed Animation.__@propertyEventListeners@3498895
    Animation.__@propertyEventListeners@3498895 was removed in happy-dom 21.0.2 npmjs.com
  • Removed Attr.__@affectsCache@3499044
    Attr.__@affectsCache@3499044 was removed in happy-dom 21.0.2 npmjs.com
  • Removed Attr.__@assignedToSlot@3499040
    Attr.__@assignedToSlot@3499040 was removed in happy-dom 21.0.2 npmjs.com
  • Removed Attr.__@cache@3499042
    Attr.__@cache@3499042 was removed in happy-dom 21.0.2 npmjs.com
  • Removed Attr.__@childNodes@3499038
    Attr.__@childNodes@3499038 was removed in happy-dom 21.0.2 npmjs.com
  • Removed Attr.__@clearCache@3499065
    Attr.__@clearCache@3499065 was removed in happy-dom 21.0.2 npmjs.com
  • Removed Attr.__@connectedToDocument@3499071
    Attr.__@connectedToDocument@3499071 was removed in happy-dom 21.0.2 npmjs.com

And 416 more in this version.

21.0.1

426 breaking changes, first published October 12, 2026.

  • Removed AbortController.__@window@3515465
    AbortController.__@window@3515465 was removed in happy-dom 21.0.1 npmjs.com
  • Removed AbortSignal.__@aborted@3515481
    AbortSignal.__@aborted@3515481 was removed in happy-dom 21.0.1 npmjs.com
  • Removed AbortSignal.__@reason@3515483
    AbortSignal.__@reason@3515483 was removed in happy-dom 21.0.1 npmjs.com
  • Removed Animation.__@propertyEventListeners@3515541
    Animation.__@propertyEventListeners@3515541 was removed in happy-dom 21.0.1 npmjs.com
  • Removed Attr.__@affectsCache@3515690
    Attr.__@affectsCache@3515690 was removed in happy-dom 21.0.1 npmjs.com
  • Removed Attr.__@assignedToSlot@3515686
    Attr.__@assignedToSlot@3515686 was removed in happy-dom 21.0.1 npmjs.com
  • Removed Attr.__@cache@3515688
    Attr.__@cache@3515688 was removed in happy-dom 21.0.1 npmjs.com
  • Removed Attr.__@childNodes@3515684
    Attr.__@childNodes@3515684 was removed in happy-dom 21.0.1 npmjs.com
  • Removed Attr.__@clearCache@3515711
    Attr.__@clearCache@3515711 was removed in happy-dom 21.0.1 npmjs.com
  • Removed Attr.__@connectedToDocument@3515717
    Attr.__@connectedToDocument@3515717 was removed in happy-dom 21.0.1 npmjs.com

And 416 more in this version.

21.0.0

428 breaking changes, first published October 11, 2026.

  • Removed AbortController.__@window@2742649
    AbortController.__@window@2742649 was removed in happy-dom 21.0.0 npmjs.com
  • Removed AbortSignal.__@aborted@2742665
    AbortSignal.__@aborted@2742665 was removed in happy-dom 21.0.0 npmjs.com
  • Removed AbortSignal.__@reason@2742667
    AbortSignal.__@reason@2742667 was removed in happy-dom 21.0.0 npmjs.com
  • Removed Animation.__@propertyEventListeners@2742725
    Animation.__@propertyEventListeners@2742725 was removed in happy-dom 21.0.0 npmjs.com
  • Removed Attr.__@affectsCache@2742874
    Attr.__@affectsCache@2742874 was removed in happy-dom 21.0.0 npmjs.com
  • Removed Attr.__@assignedToSlot@2742870
    Attr.__@assignedToSlot@2742870 was removed in happy-dom 21.0.0 npmjs.com
  • Removed Attr.__@cache@2742872
    Attr.__@cache@2742872 was removed in happy-dom 21.0.0 npmjs.com
  • Removed Attr.__@childNodes@2742868
    Attr.__@childNodes@2742868 was removed in happy-dom 21.0.0 npmjs.com
  • Removed Attr.__@clearCache@2742895
    Attr.__@clearCache@2742895 was removed in happy-dom 21.0.0 npmjs.com
  • Removed Attr.__@connectedToDocument@2742901
    Attr.__@connectedToDocument@2742901 was removed in happy-dom 21.0.0 npmjs.com

And 418 more in this version.

20.14.6

426 breaking changes, first published October 8, 2026.

  • Removed AbortController.__@window@3580263
    AbortController.__@window@3580263 was removed in happy-dom 20.14.6 npmjs.com
  • Removed AbortSignal.__@aborted@3580279
    AbortSignal.__@aborted@3580279 was removed in happy-dom 20.14.6 npmjs.com
  • Removed AbortSignal.__@reason@3580281
    AbortSignal.__@reason@3580281 was removed in happy-dom 20.14.6 npmjs.com
  • Removed Animation.__@propertyEventListeners@3580339
    Animation.__@propertyEventListeners@3580339 was removed in happy-dom 20.14.6 npmjs.com
  • Removed Attr.__@affectsCache@3580488
    Attr.__@affectsCache@3580488 was removed in happy-dom 20.14.6 npmjs.com
  • Removed Attr.__@assignedToSlot@3580484
    Attr.__@assignedToSlot@3580484 was removed in happy-dom 20.14.6 npmjs.com
  • Removed Attr.__@cache@3580486
    Attr.__@cache@3580486 was removed in happy-dom 20.14.6 npmjs.com
  • Removed Attr.__@childNodes@3580482
    Attr.__@childNodes@3580482 was removed in happy-dom 20.14.6 npmjs.com
  • Removed Attr.__@clearCache@3580509
    Attr.__@clearCache@3580509 was removed in happy-dom 20.14.6 npmjs.com
  • Removed Attr.__@connectedToDocument@3580515
    Attr.__@connectedToDocument@3580515 was removed in happy-dom 20.14.6 npmjs.com

And 416 more in this version.

Check your code

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