# modifyClass failed with a warning

**URL:** https://meta.discourse.org/t/modifyclass-failed-with-a-warning/239535
**Category:** Development
**Created:** [September 20, 2022, 10:45am UTC](https://meta.discourse.org/t/modifyclass-failed-with-a-warning/239535 "2022-09-20T10:45:46Z")
**Posts on this page:** 1
**Showing post:** 6

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### Author: ![david](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/david/32/157490_2.png) [@david](https://meta.discourse.org/u/david)
#### Post date: [April 18, 2023, 10:40am UTC](https://meta.discourse.org/t/modifyclass-failed-with-a-warning/239535/6 "2023-04-18T10:40:06Z")

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> [@Using modifyClass to change core behavior](https://meta.discourse.org/t/using-modifyclass-for-objects-which-are-initialized-early-in-boot/262064):
>
> For advanced themes and plugins, Discourse offers the modifyClass system. This allows you to extend and override functionality in many of core’s javascript classes. When to use modifyClass modifyClass should be a last resort, when your customization cannot be made via Discourse’s more stable customization APIs (e.g. plugin-api methods, plugin outlets, transformers). Core’s code can change at any time. And therefore, customizations made via modifyClass could break at any time. When using this A…

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