CustomEvent breaking SSR #64175

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1. JoostK commented on Oct 1, 2025

   

   JoostK

   on Oct 1, 2025

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   I'd request a bit more information here, ideally a proper reproduction that showcases the issue they're experiencing.
2. thePunderWoman

   added

   area: serverIssues related to server-side renderingIssues related to server-side rendering

   on Oct 1, 2025
3. ngbot

   added this to the needsTriage milestone on Oct 1, 2025
4. JeanMeche commented on Oct 1, 2025

   

   JeanMeche

   on Oct 1, 2025

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   cc @AlemTuzlak

   👀React with 👀1Reacted by Alem Tuzlak
5. AlemTuzlak commented on Oct 1, 2025

   

   AlemTuzlak

   on Oct 1, 2025

   Last edited by AlemTuzlak

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   Just dispatch a CustomEvent on the window object with window.dispatchEvent, and it will crash. The server dies with an error that CustomEvent can't be dispatched.

   But to be completely honest, I wouldn't expect window to be defined at all on the server, so I'm not sure what the right approach is. I don't like shims, and I'd prefer the environment to reflect what it is, in this case, a server without a window.
6. JeanMeche commented on Oct 1, 2025

   

   JeanMeche

   on Oct 1, 2025

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   Angular does DOM emulation with a fork of Domino: https://github.com/angular/domino
7. alan-agius4 commented on Oct 13, 2025

   

   alan-agius4

   on Oct 13, 2025

   Last edited by alan-agius4

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   @AlemTuzlak, to give you a precise solution, could you provide a bit more context about what you're trying to achieve with this event? For an SSR compliant application you typically need to guard browser-only APIs. The best way to handle this is either by checking with isPlatformBrowser or the recommended approach is to place browser-specific code in afterNextRender and afterEveryRender hooks.

   One other alternative would be to use the Document injection token to get the "Window" which will result in the event to also work in SSR.

   const doc = inject(DOCUMENT);
   const event = new CustomEvent('myCustomEvent', { detail: { data: 'hello' } });
   // doc.defaultView can be null but it will be defined in SSR.
   doc.defaultView?.addEventListener('myCustomEvent', (e) => console.log(e));
   doc.defaultView?.dispatchEvent(event);
8. alan-agius4

   added

   needs: clarificationThis issue needs additional clarification from the reporter before the team can investigate.This issue needs additional clarification from the reporter before the team can investigate.

   on Oct 13, 2025
9. alan-agius4 commented on Oct 21, 2025

   

   alan-agius4

   on Oct 21, 2025

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   Closing as per above.
10. alan-agius4

    closed this as not plannedon Oct 21, 2025
11. AlemTuzlak commented on Oct 21, 2025

    

    AlemTuzlak

    on Oct 21, 2025

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    @alan-agius4 I've fixed it already on our end by specifically checking if the code is running in angular, the issue I had was that Angular was "lying" about the environment, it has the window object defined on the server but uses an emulated version of that as Jean mentioned above. I can't use anything from Angular as framework agnostic software can't be framework agnostic if it imports methods from Angular, I just check if the actual normal dispatchEvent behavior works and then use a shim designed for angular by creating a normal event.

    Like mentioned in my tweet, emulating stuff that doesn't exist in places it shouldn't exist is a very frustrating experience that usually leads to a lot of external things breaking due to detecting things that shouldn't be there.
12. angular-automatic-lock-bot commented on Nov 21, 2025

    

    angular-automatic-lock-botBot

    on Nov 21, 2025

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    This issue has been automatically locked due to inactivity.
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13. angular-automatic-lock-bot

    locked and limited conversation to collaborators on Nov 21, 2025