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fix: preserve native Event/dispatchEvent in jsdom setup for Deno compatibility #9

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Merged
Lojhan merged 1 commit into from
Apr 5, 2026
Merged

fix: preserve native Event/dispatchEvent in jsdom setup for Deno compatibility #9

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22 changes: 20 additions & 2 deletions src/dom-env.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,15 @@ export const setupJsdomEnvironment = async (
);
}

// Save native event primitives before jsdom replaces them.
// Deno's runtime teardown fires dispatchLoadEvent() on process exit using
// its own native Event constructor — if jsdom's Event is installed instead,
// setTarget() receives undefined and throws "Cannot set properties of
// undefined (setting 'target')".
const existingDispatchEvent = globalThis.dispatchEvent;
const existingEvent = globalThis.Event;
const existingCustomEvent = globalThis.CustomEvent;

const { JSDOM } = mod;
const dom = new JSDOM('', {
url: options.runtimeOptions.domUrl,
Expand All @@ -96,11 +105,20 @@ export const setupJsdomEnvironment = async (
defineGlobal('Node', dom.window.Node);
defineGlobal('Text', dom.window.Text);
defineGlobal('SVGElement', dom.window.SVGElement);
defineGlobal('Event', dom.window.Event);
defineGlobal('CustomEvent', dom.window.CustomEvent);
defineGlobal('MutationObserver', dom.window.MutationObserver);
defineGlobal('requestAnimationFrame', dom.window.requestAnimationFrame);
defineGlobal('cancelAnimationFrame', dom.window.cancelAnimationFrame);

// Prefer the runtime's native Event constructors so that Deno's internal
// event dispatch (e.g. load/beforeunload) continues to work correctly.
defineGlobal('Event', typeof existingEvent === 'function' ? existingEvent : dom.window.Event);
defineGlobal('CustomEvent', typeof existingCustomEvent === 'function' ? existingCustomEvent : dom.window.CustomEvent);

if (typeof existingDispatchEvent === 'function') {
globalThis.dispatchEvent = existingDispatchEvent;
} else {
globalThis.dispatchEvent = dom.window.dispatchEvent.bind(dom.window) as unknown as typeof globalThis.dispatchEvent;
}
}

applyReactActEnvironment(Boolean(options.enableReactActEnvironment));
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