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conformance · v151

v151 · animation-accessor-on-animation-and-transition-events — conformance probe

9 assertions drawn from the spec. Each is a single contract the spec text makes. Pass/fail reflects what this browser executed; blocked means the contract was not run because it needs user mediation, hardware, or another unavailable precondition. Open the page in Chrome stable / canary / Firefox / Safari to compare.

browser: spec: https://drafts.csswg.org/css-animations-2/#interface-animationevent chromestatus: #6046278267043840 generated 2026-07-24T21:20:00Z by kimi-k3-manual-iteration
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pass
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id contract kind verdict detail
animationevent-interface-exists window.AnimationEvent exists — the event interface the read-only animation attribute is added to. spec ↗ exists
transitionevent-interface-exists window.TransitionEvent exists — the companion event interface getting the same attribute. spec ↗ exists
cssanimation-interface-exists window.CSSAnimation exists — the Animation subclass returned for CSS-generated animations. spec ↗ exists
csstransition-interface-exists window.CSSTransition exists — the Animation subclass returned for CSS-generated transitions. spec ↗ exists
animationevent-accessor-on-prototype 'animation' is a member of AnimationEvent.prototype — the new read-only INSTANCE attribute returning the CSSAnimation? that fired the event (Chrome 151 per the milestone listing; BCD also records Firefox 152 / Safari 27). spec ↗ script
transitionevent-accessor-on-prototype 'animation' is a member of TransitionEvent.prototype — the companion INSTANCE attribute returning the CSSTransition? that fired the event. spec ↗ script
accessor-not-static-on-constructors The accessor is an instance attribute, never a static on the constructors: neither AnimationEvent.animation nor TransitionEvent.animation exists as a constructor property (this holds whether or not the accessor is implemented). spec ↗ script
synthetic-animationevent-animation-null The AnimationEvent attribute is nullable: when the accessor exists, a synthetic event constructed without the init member reports animation === null (not undefined or a fabricated Animation). spec ↗ script
synthetic-transitionevent-animation-null The TransitionEvent attribute is likewise nullable: when the accessor exists, a synthetic event constructed without the init member reports animation === null. spec ↗ script