fix: improve support for configFile: false use in kit (#319)

* fix: allow kit options inline to enable sveltekit passing loaded config without warning

* fix: do not restart vite devserver on config file changes with

* chore: improve docs

Co-authored-by: Bjorn Lu <[email protected]>

Co-authored-by: Bjorn Lu <[email protected]>

Author: dominikg

.changeset/silver-readers-wait.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/vite-plugin-svelte': patch
+---
+
+do not warn if kit options are passed as inline config

.changeset/young-rice-bathe.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/vite-plugin-svelte': patch
+---
+
+do not restart vite devserver on changes of svelte config when `configFile: false` is set

docs/config.md

@@ -36,8 +36,6 @@ export default defineConfig({
 });
 ```
 
-> To prevent reading the default config, use `configFile: false`.
-
 A basic Svelte config looks like this:
 
 ```js
@@ -56,6 +54,25 @@ Depending on Node's mode, make sure you're using the correct extension and synta
 
 > Try to stick with the `.js` extension whenever possible.
 
+### Disable automatic handling of Svelte config
+
+Use `configFile: false` to prevent `vite-plugin-svelte` from reading the config file or restarting the Vite dev server when it changes.
+
+```js
+export default defineConfig({
+  plugins: [
+    svelte({
+      configFile: false
+      // your svelte config here
+    })
+  ]
+});
+```
+
+> Warning:
+> This option primarily exists for frameworks like SvelteKit that do their own parsing of Svelte config and control the Vite dev server.
+> You are responsible to provide the complete inline config when used.
+
 ## Svelte options
 
 These options are specific to the Svelte compiler and are generally shared across many bundler integrations.

packages/vite-plugin-svelte/src/utils/options.ts

@@ -37,7 +37,8 @@ const knownOptions = new Set([
 	'hot',
 	'ignorePluginPreprocessors',
 	'disableDependencyReinclusion',
-	'experimental'
+	'experimental',
+	'kit'
 ]);
 
 export function validateInlineOptions(inlineOptions?: Partial<Options>) {
@@ -355,7 +356,7 @@ export interface Options {
 	/**
 	 * Path to a svelte config file, either absolute or relative to Vite root
 	 *
-	 * set to `false` to skip reading config from a file
+	 * set to `false` to ignore the svelte config file
 	 *
 	 * @see https://vitejs.dev/config/#root
 	 */

packages/vite-plugin-svelte/src/utils/watch.ts

@@ -58,30 +58,34 @@ export function setupWatchers(
 		}
 	};
 
-	const possibleSvelteConfigs = knownSvelteConfigNames.map((cfg) => path.join(root, cfg));
-	const restartOnConfigAdd = (filename: string) => {
-		if (possibleSvelteConfigs.includes(filename)) {
-			triggerViteRestart(filename);
-		}
-	};
-
-	const restartOnConfigChange = (filename: string) => {
-		if (filename === svelteConfigFile) {
-			triggerViteRestart(filename);
-		}
-	};
-
 	// collection of watcher listeners by event
 	const listenerCollection = {
 		add: [] as Array<Function>,
 		change: [emitChangeEventOnDependants],
 		unlink: [removeUnlinkedFromCache, emitChangeEventOnDependants]
 	};
-	if (svelteConfigFile) {
-		listenerCollection.change.push(restartOnConfigChange);
-		listenerCollection.unlink.push(restartOnConfigChange);
-	} else {
-		listenerCollection.add.push(restartOnConfigAdd);
+
+	if (svelteConfigFile !== false) {
+		// configFile false means we ignore the file and external process is responsible
+		const possibleSvelteConfigs = knownSvelteConfigNames.map((cfg) => path.join(root, cfg));
+		const restartOnConfigAdd = (filename: string) => {
+			if (possibleSvelteConfigs.includes(filename)) {
+				triggerViteRestart(filename);
+			}
+		};
+
+		const restartOnConfigChange = (filename: string) => {
+			if (filename === svelteConfigFile) {
+				triggerViteRestart(filename);
+			}
+		};
+
+		if (svelteConfigFile) {
+			listenerCollection.change.push(restartOnConfigChange);
+			listenerCollection.unlink.push(restartOnConfigChange);
+		} else {
+			listenerCollection.add.push(restartOnConfigAdd);
+		}
 	}
 
 	Object.entries(listenerCollection).forEach(([evt, listeners]) => {