A use case for this that I recently encountered is that, there is the Theme interface in material UI library for react and you can import it. After that you can create the same interface with extra custom properties like company specific color palette and standard size configs and declaration merging automatically adds these extended properties to that and your app can consume both the standard stuff in the theme interface and you get intellisense for your custom extensions as well. That's pretty cool in my opinion !
A use case for this that I recently encountered is that, there is the Theme interface in material UI library for react and you can import it. After that you can create the same interface with extra custom properties like company specific color palette and standard size configs and declaration merging automatically adds these extended properties to that and your app can consume both the standard stuff in the theme interface and you get intellisense for your custom extensions as well. That's pretty cool in my opinion !
Oh this is a perfect example! Thanks for sharing!