[Custom client.js] Partial load on default paths (#447)

* [Custom client.js] Partial load on default paths

* more readme

* format

* better readme

* correct path

Author: mishig25

kit/package.json

@@ -3,8 +3,9 @@
 	"version": "0.0.1",
 	"private": true,
 	"scripts": {
-		"dev": "vite dev",
-		"build": "rm -Rf src/routes/__pycache__ && vite build && node postprocess && ./postbuild.sh",
+		"custom-svelte-client": "node ./svelteKitCustomClient/replace",
+		"dev": "npm run custom-svelte-client && vite dev",
+		"build": "npm run custom-svelte-client && rm -Rf src/routes/__pycache__ && vite build && node postprocess && ./postbuild.sh",
 		"preview": "vite preview",
 		"check": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json",
 		"check:watch": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json --watch",

kit/svelteKitCustomClient/README.md

@@ -0,0 +1,21 @@
+# Custom `sveltekit client.js` file
+
+Sveltekit handles [internal routes](https://kit.svelte.dev/docs/routing) by:
+
+1. partially loading changed components
+2. updating the browser's [history](https://developer.mozilla.org/en-US/docs/Web/API/History)
+
+which makes the user experience better by not loading/reloading pages completely from scratch.
+
+### Hugging Face docs
+
+In [hf docs](https://huggingface.co/docs), we have these redirection rules:
+
+```
+hf.co/docs/lib/page -> hf.co/docs/lib/default_version/default_lang/page
+hf.co/docs/lib/version/page -> hf.co/docs/lib/version/default_lang/page
+```
+
+However, these rules were being handled as external routes by SvelteKit without taking advantage of partial reloadings. I've tried using [$app/navigation](https://kit.svelte.dev/docs/modules#$app-navigation) without success. Therefore, the simplest solution was: overwriting [sveltekit client.js](https://github.com/sveltejs/kit/blob/master/packages/kit/src/runtime/client/client.js) to handle hf doc routes accordingly.
+
+Specifically, this [custom client.js](https://github.com/huggingface/doc-builder/blob/ab03d33801595579591ac8cdc49514c4f59fe068/kit/svelteKitCustomClient/client.js) is identical to [sveltekit client.js](https://github.com/sveltejs/kit/blob/master/packages/kit/src/runtime/client/client.js) with only one difference: addition and usage of [getHfDocFullPath function](https://github.com/huggingface/doc-builder/blob/ab03d33801595579591ac8cdc49514c4f59fe068/kit/svelteKitCustomClient/client.js#L43), which makes it possible for hf redirected paths (as described above) to be considered as `internal routes` and take full advantage of partial loading.