Allow configuration of swapComponent like resolveComponent to make automatic props transformation possible or introduce transformation function for setPage

[Josefikos]

It would be great to be able to modify props before they reach components. The best example and use case is with Date objects.

For the application, it is a regular string, but thanks to regex on value or other methods or the key name in the object, we can automatically convert it to a Date object.

The components then receive the Date object directly instead of a string, which significantly simplifies subsequent work in the application without the need to define additional variables.

The first mount of the application can transform props during the setup function in createInertiaApp, which unfortunately is not sufficient for navigating to other pages and inertia requests.

Thanks to the customizability of swapComponent, similar transformations could be created for values other than just time. For example, converting numbers to the Decimal class or other specific business logic.

Since swapComponent uses unexported setPage and resolveRenderProps and sets other local variables such as component, page, key, and renderProps, it is not possible to make swapComponent easily customizable without further changes. A wrapper transformation function when assigning data to the page variable would be more than sufficient.

setPage inside current svelte adapter

  if (!isServer) {
    router.init<ResolvedComponent>({
      initialPage,
      resolveComponent,
      swapComponent: async (args) => {
        component = args.component
        page = args.page
        key = args.preserveState ? key : Date.now()

        renderProps = resolveRenderProps(component, page, key)
        setPage(page)
      },
    })
  }

Possible fueature implementation

  if (!isServer) {
    router.init<ResolvedComponent>({
      initialPage,
      resolveComponent,
      swapComponent: async (args) => {
        component = args.component
        page = transformData(args.page)
        key = args.preserveState ? key : Date.now()

        renderProps = resolveRenderProps(component, page, key)
        setPage(page)
      },
    })
  }

transformData is passed as simple prop into App component. Default value can be simple method like (data) => data.