fix: use arrow functions over bound funcs

.changeset/gentle-feet-kiss.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: use arrow functions instead of bound functions

eslint.config.js

@@ -26,7 +26,8 @@ export default [
 		rules: {
 			'@typescript-eslint/await-thenable': 'error',
 			'@typescript-eslint/no-unused-expressions': 'off',
-			'@typescript-eslint/require-await': 'error'
+			'@typescript-eslint/require-await': 'error',
+			'@typescript-eslint/unbound-method': 'error'
 		},
 		ignores: [
 			'packages/adapter-node/rollup.config.js',

packages/kit/src/exports/public.d.ts

@@ -34,7 +34,7 @@ export interface Adapter {
 	 * This function is called after SvelteKit has built your app.
 	 * @param builder An object provided by SvelteKit that contains methods for adapting the app
 	 */
-	adapt(builder: Builder): MaybePromise<void>;
+	adapt: (builder: Builder) => MaybePromise<void>;
 	/**
 	 * Checks called during dev and build to determine whether specific features will work in production with this adapter
 	 */
@@ -49,7 +49,7 @@ export interface Adapter {
 	 * Creates an `Emulator`, which allows the adapter to influence the environment
 	 * during dev, build and prerendering
 	 */
-	emulate?(): MaybePromise<Emulator>;
+	emulate?: () => MaybePromise<Emulator>;
 }
 
 export type LoadProperties<input extends Record<string, any> | void> = input extends void
@@ -685,7 +685,7 @@ export interface KitConfig {
  */
 export type Handle = (input: {
 	event: RequestEvent;
-	resolve(event: RequestEvent, opts?: ResolveOptions): MaybePromise<Response>;
+	resolve: (event: RequestEvent, opts?: ResolveOptions) => MaybePromise<Response>;
 }) => MaybePromise<Response>;
 
 /**
@@ -791,14 +791,14 @@ export interface LoadEvent<
 	 *
 	 * `setHeaders` has no effect when a `load` function runs in the browser.
 	 */
-	setHeaders(headers: Record<string, string>): void;
+	setHeaders: (headers: Record<string, string>) => void;
 	/**
 	 * `await parent()` returns data from parent `+layout.js` `load` functions.
 	 * Implicitly, a missing `+layout.js` is treated as a `({ data }) => data` function, meaning that it will return and forward data from parent `+layout.server.js` files.
 	 *
 	 * Be careful not to introduce accidental waterfalls when using `await parent()`. If for example you only want to merge parent data into the returned output, call it _after_ fetching your other data.
 	 */
-	parent(): Promise<ParentData>;
+	parent: () => Promise<ParentData>;
 	/**
 	 * This function declares that the `load` function has a _dependency_ on one or more URLs or custom identifiers, which can subsequently be used with [`invalidate()`](https://svelte.dev/docs/kit/$app-navigation#invalidate) to cause `load` to rerun.
 	 *
@@ -836,7 +836,7 @@ export interface LoadEvent<
 	 * <button on:click={increase}>Increase Count</button>
 	 * ```
 	 */
-	depends(...deps: Array<`${string}:${string}`>): void;
+	depends: (...deps: Array<`${string}:${string}`>) => void;
 	/**
 	 * Use this function to opt out of dependency tracking for everything that is synchronously called within the callback. Example:
 	 *
@@ -850,7 +850,7 @@ export interface LoadEvent<
 	 * }
 	 * ```
 	 */
-	untrack<T>(fn: () => T): T;
+	untrack: <T>(fn: () => T) => T;
 }
 
 export interface NavigationEvent<
@@ -1059,7 +1059,7 @@ export interface RequestEvent<
 	/**
 	 * The client's IP address, set by the adapter.
 	 */
-	getClientAddress(): string;
+	getClientAddress: () => string;
 	/**
 	 * Contains custom data that was added to the request within the [`server handle hook`](https://svelte.dev/docs/kit/hooks#Server-hooks-handle).
 	 */
@@ -1107,7 +1107,7 @@ export interface RequestEvent<
 	 *
 	 * You cannot add a `set-cookie` header with `setHeaders` — use the [`cookies`](https://svelte.dev/docs/kit/@sveltejs-kit#Cookies) API instead.
 	 */
-	setHeaders(headers: Record<string, string>): void;
+	setHeaders: (headers: Record<string, string>) => void;
 	/**
 	 * The requested URL.
 	 */
@@ -1140,20 +1140,20 @@ export interface ResolveOptions {
 	 * but they will always be split at sensible boundaries such as `%sveltekit.head%` or layout/page components.
 	 * @param input the html chunk and the info if this is the last chunk
 	 */
-	transformPageChunk?(input: { html: string; done: boolean }): MaybePromise<string | undefined>;
+	transformPageChunk?: (input: { html: string; done: boolean }) => MaybePromise<string | undefined>;
 	/**
 	 * Determines which headers should be included in serialized responses when a `load` function loads a resource with `fetch`.
 	 * By default, none will be included.
 	 * @param name header name
 	 * @param value header value
 	 */
-	filterSerializedResponseHeaders?(name: string, value: string): boolean;
+	filterSerializedResponseHeaders?: (name: string, value: string) => boolean;
 	/**
 	 * Determines what should be added to the `<head>` tag to preload it.
 	 * By default, `js` and `css` files will be preloaded.
 	 * @param input the type of the file and its path
 	 */
-	preload?(input: { type: 'font' | 'css' | 'js' | 'asset'; path: string }): boolean;
+	preload?: (input: { type: 'font' | 'css' | 'js' | 'asset'; path: string }) => boolean;
 }
 
 export interface RouteDefinition<Config = any> {
@@ -1222,7 +1222,7 @@ export interface ServerLoadEvent<
 	 *
 	 * Be careful not to introduce accidental waterfalls when using `await parent()`. If for example you only want to merge parent data into the returned output, call it _after_ fetching your other data.
 	 */
-	parent(): Promise<ParentData>;
+	parent: () => Promise<ParentData>;
 	/**
 	 * This function declares that the `load` function has a _dependency_ on one or more URLs or custom identifiers, which can subsequently be used with [`invalidate()`](https://svelte.dev/docs/kit/$app-navigation#invalidate) to cause `load` to rerun.
 	 *
@@ -1260,7 +1260,7 @@ export interface ServerLoadEvent<
 	 * <button on:click={increase}>Increase Count</button>
 	 * ```
 	 */
-	depends(...deps: string[]): void;
+	depends: (...deps: string[]) => void;
 	/**
 	 * Use this function to opt out of dependency tracking for everything that is synchronously called within the callback. Example:
 	 *
@@ -1274,7 +1274,7 @@ export interface ServerLoadEvent<
 	 * }
 	 * ```
 	 */
-	untrack<T>(fn: () => T): T;
+	untrack: <T>(fn: () => T) => T;
 }
 
 /**
@@ -1345,7 +1345,7 @@ export type SubmitFunction<
 	formElement: HTMLFormElement;
 	controller: AbortController;
 	submitter: HTMLElement | null;
-	cancel(): void;
+	cancel: () => void;
 }) => MaybePromise<
 	| void
 	| ((opts: {
@@ -1358,7 +1358,7 @@ export type SubmitFunction<
 			 * @param options Set `reset: false` if you don't want the `<form>` values to be reset after a successful submission.
 			 * @param invalidateAll Set `invalidateAll: false` if you don't want the action to call `invalidateAll` after submission.
 			 */
-			update(options?: { reset?: boolean; invalidateAll?: boolean }): Promise<void>;
+			update: (options?: { reset?: boolean; invalidateAll?: boolean }) => Promise<void>;
 	  }) => void)
 >;
 

packages/kit/src/exports/vite/dev/index.js

@@ -384,6 +384,7 @@ export async function dev(vite, vite_config, svelte_config) {
 		});
 	}
 	align_exports();
+	// eslint-disable-next-line @typescript-eslint/unbound-method -- We'll pass `this` back to it later
 	const ws_send = vite.ws.send;
 	/** @param {any} args */
 	vite.ws.send = function (...args) {

packages/kit/src/runtime/app/stores.js

@@ -56,7 +56,7 @@ export const navigating = {
  * A readable store whose initial value is `false`. If [`version.pollInterval`](https://svelte.dev/docs/kit/configuration#version) is a non-zero value, SvelteKit will poll for new versions of the app and update the store value to `true` when it detects one. `updated.check()` will force an immediate check, regardless of polling.
  *
  * On the server, this store can only be subscribed to during component initialization. In the browser, it can be subscribed to at any time.
- * @type {import('svelte/store').Readable<boolean> & { check(): Promise<boolean> }}
+ * @type {import('svelte/store').Readable<boolean> & { check: () => Promise<boolean> }}
  */
 export const updated = {
 	subscribe(fn) {

packages/kit/src/runtime/client/client.js

@@ -88,12 +88,14 @@ if (DEV && BROWSER) {
 		);
 	};
 
+	// eslint-disable-next-line @typescript-eslint/unbound-method -- We'll pass `history` as `this`
 	const push_state = history.pushState;
 	history.pushState = (...args) => {
 		warn();
 		return push_state.apply(history, args);
 	};
 
+	// eslint-disable-next-line @typescript-eslint/unbound-method -- We'll pass `history` as `this`
 	const replace_state = history.replaceState;
 	history.replaceState = (...args) => {
 		warn();
@@ -1374,6 +1376,7 @@ async function navigate({
 			[STATES_KEY]: state
 		};
 
+		// eslint-disable-next-line @typescript-eslint/unbound-method -- We'll pass `history` as `this`
 		const fn = replace_state ? history.replaceState : history.pushState;
 		fn.call(history, entry, '', url);
 

packages/kit/src/runtime/server/cookie.js

@@ -64,6 +64,7 @@ export function get_cookies(request, url, trailing_slash) {
 				return c.value;
 			}
 
+			// eslint-disable-next-line @typescript-eslint/unbound-method -- Fixed in `cookie@1.0.0`'s types
 			const decoder = opts?.decode || decodeURIComponent;
 			const req_cookies = parse(header, { decode: decoder });
 			const cookie = req_cookies[name]; // the decoded string or undefined
@@ -92,6 +93,7 @@ export function get_cookies(request, url, trailing_slash) {
 		 * @param {import('cookie').CookieParseOptions} opts
 		 */
 		getAll(opts) {
+			// eslint-disable-next-line @typescript-eslint/unbound-method -- Fixed in `cookie@1.0.0`'s types
 			const decoder = opts?.decode || decodeURIComponent;
 			const cookies = parse(header, { decode: decoder });
 
@@ -161,6 +163,7 @@ export function get_cookies(request, url, trailing_slash) {
 			if (!domain_matches(destination.hostname, cookie.options.domain)) continue;
 			if (!path_matches(destination.pathname, cookie.options.path)) continue;
 
+			// eslint-disable-next-line @typescript-eslint/unbound-method -- Fixed in `cookie@1.0.0`'s types
 			const encoder = cookie.options.encode || encodeURIComponent;
 			combined_cookies[cookie.name] = encoder(cookie.value);
 		}

packages/kit/src/runtime/server/page/load_data.js

@@ -340,6 +340,7 @@ export function create_universal_fetch(event, state, fetched, csr, resolve_opts)
 
 		if (csr) {
 			// ensure that excluded headers can't be read
+			// eslint-disable-next-line @typescript-eslint/unbound-method -- We'll pass `response.headers` as `this`
 			const get = response.headers.get;
 			response.headers.get = (key) => {
 				const lower = key.toLowerCase();

packages/kit/src/types/internal.d.ts

@@ -32,16 +32,16 @@ export interface ServerModule {
 }
 
 export interface ServerInternalModule {
-	set_assets(path: string): void;
-	set_building(): void;
-	set_manifest(manifest: SSRManifest): void;
-	set_prerendering(): void;
-	set_private_env(environment: Record<string, string>): void;
-	set_public_env(environment: Record<string, string>): void;
-	set_read_implementation(implementation: (path: string) => ReadableStream): void;
-	set_safe_public_env(environment: Record<string, string>): void;
-	set_version(version: string): void;
-	set_fix_stack_trace(fix_stack_trace: (error: unknown) => string): void;
+	set_assets: (path: string) => void;
+	set_building: () => void;
+	set_manifest: (manifest: SSRManifest) => void;
+	set_prerendering: () => void;
+	set_private_env: (environment: Record<string, string>) => void;
+	set_public_env: (environment: Record<string, string>) => void;
+	set_read_implementation: (implementation: (path: string) => ReadableStream) => void;
+	set_safe_public_env: (environment: Record<string, string>) => void;
+	set_version: (version: string) => void;
+	set_fix_stack_trace: (fix_stack_trace: (error: unknown) => string) => void;
 }
 
 export interface Asset {
@@ -404,7 +404,7 @@ export interface SSRRoute {
 
 export interface SSRState {
 	fallback?: string;
-	getClientAddress(): string;
+	getClientAddress: () => string;
 	/**
 	 * True if we're currently attempting to render an error page
 	 */

packages/kit/src/types/private.d.ts

@@ -20,13 +20,15 @@ export interface AdapterEntry {
 	 * - Fallback pages: `/foo/[c]` is a fallback for `/foo/a-[b]`, and `/[...catchall]` is a fallback for all routes
 	 * - Grouping routes that share a common `config`: `/foo` should be deployed to the edge, `/bar` and `/baz` should be deployed to a serverless function
 	 */
-	filter(route: RouteDefinition): boolean;
+	filter: (route: RouteDefinition) => boolean;
 
 	/**
 	 * A function that is invoked once the entry has been created. This is where you
 	 * should write the function to the filesystem and generate redirect manifests.
 	 */
-	complete(entry: { generateManifest(opts: { relativePath: string }): string }): MaybePromise<void>;
+	complete: (entry: {
+		generateManifest(opts: { relativePath: string }): string;
+	}) => MaybePromise<void>;
 }
 
 // Based on https://github.com/josh-hemphill/csp-typed-directives/blob/latest/src/csp.types.ts