Types

/** @type {import('@sveltejs/kit').RequestHandler<{
	foo: string;
	bar: string;
	baz: string
  }>} */
export async function 
function GET({ params }: {
    params: any;
}): Promise<void>
@type{import('@sveltejs/kit').RequestHandler<{
	foo: string;
	bar: string;
	baz: string
  }>}GET({ params: anyparams }) {
	// ...
}

import type { type RequestHandler<Params extends Partial<Record<string, string>> = Partial<Record<string, string>>, RouteId extends string | null = string | null> = (event: RequestEvent<Params, RouteId>) => MaybePromise<Response>
A (event: RequestEvent) => Response function exported from a +server.js file that corresponds to an HTTP verb (GET, PUT, PATCH, etc) and handles requests with that method.
It receives Params as the first generic argument, which you can skip by using generated types instead.
RequestHandler } from '@sveltejs/kit';
export const 
const GET: RequestHandler<{
    foo: string;
    bar: string;
    baz: string;
}>GET: type RequestHandler<Params extends Partial<Record<string, string>> = Partial<Record<string, string>>, RouteId extends string | null = string | null> = (event: RequestEvent<Params, RouteId>) => MaybePromise<Response>
A (event: RequestEvent) => Response function exported from a +server.js file that corresponds to an HTTP verb (GET, PUT, PATCH, etc) and handles requests with that method.
It receives Params as the first generic argument, which you can skip by using generated types instead.
RequestHandler<{
	foo: stringfoo: string;
	bar: stringbar: string;
	baz: stringbaz: string
  }> = async ({ 
params: {
    foo: string;
    bar: string;
    baz: string;
}
The parameters of the current route - e.g. for a route like /blog/[slug], a { slug: string } object.
params }) => {
	// ...
};

import type * as module "@sveltejs/kit"Kit from '@sveltejs/kit';

type 
type RouteParams = {
    foo: string;
    bar: string;
    baz: string;
}RouteParams = {
	foo: stringfoo: string;
	bar: stringbar: string;
	baz: stringbaz: string;
};

export type type RequestHandler = (event: Kit.RequestEvent<RouteParams, string | null>) => MaybePromise<Response>RequestHandler = module "@sveltejs/kit"Kit.type RequestHandler<Params extends Partial<Record<string, string>> = Partial<Record<string, string>>, RouteId extends string | null = string | null> = (event: Kit.RequestEvent<Params, RouteId>) => MaybePromise<Response>
A (event: RequestEvent) => Response function exported from a +server.js file that corresponds to an HTTP verb (GET, PUT, PATCH, etc) and handles requests with that method.
It receives Params as the first generic argument, which you can skip by using generated types instead.
RequestHandler<
type RouteParams = {
    foo: string;
    bar: string;
    baz: string;
}RouteParams>;
export type type PageLoad = (event: Kit.LoadEvent<RouteParams, Record<string, any> | null, Record<string, any>, string | null>) => MaybePromise<void | Record<string, any>>PageLoad = module "@sveltejs/kit"Kit.type Load<Params extends Partial<Record<string, string>> = Partial<Record<string, string>>, InputData extends Record<string, unknown> | null = Record<string, any> | null, ParentData extends Record<string, unknown> = Record<...>, OutputData extends Record<string, unknown> | void = void | Record<...>, RouteId extends string | null = string | null> = (event: Kit.LoadEvent<Params, InputData, ParentData, RouteId>) => MaybePromise<OutputData>
The generic form of PageLoad and LayoutLoad. You should import those from ./$types (see generated types)
rather than using Load directly.
Load<
type RouteParams = {
    foo: string;
    bar: string;
    baz: string;
}RouteParams>;

/** @type {import('./$types').RequestHandler} */
export async function GET({ params: RouteParams
The parameters of the current route - e.g. for a route like /blog/[slug], a { slug: string } object.
params }) {
	// ...
}

import type { type RequestHandler = (event: RequestEvent<RouteParams, string | null>) => MaybePromise<Response>RequestHandler } from './$types';

export const GET: type RequestHandler = (event: RequestEvent<RouteParams, string | null>) => MaybePromise<Response>RequestHandler = async ({ params: RouteParams
The parameters of the current route - e.g. for a route like /blog/[slug], a { slug: string } object.
params }) => {
	// ...
};

/** @type {import('./$types').PageLoad} */
export async function function load(event: LoadEvent<RouteParams, Record<string, any> | null, Record<string, any>, string | null>): MaybePromise<void | Record<string, any>>
@type{import('./$types').PageLoad}load({ params: RouteParams
The parameters of the current page - e.g. for a route like /blog/[slug], a { slug: string } object
params, 
fetch: {
    (input: RequestInfo | URL, init?: RequestInit): Promise<Response>;
    (input: string | URL | globalThis.Request, init?: RequestInit): Promise<Response>;
}
fetch is equivalent to the native fetch web API, with a few additional features:

It can be used to make credentialed requests on the server, as it inherits the cookie and authorization headers for the page request.
It can make relative requests on the server (ordinarily, fetch requires a URL with an origin when used in a server context).
Internal requests (e.g. for +server.js routes) go directly to the handler function when running on the server, without the overhead of an HTTP call.
During server-side rendering, the response will be captured and inlined into the rendered HTML by hooking into the text and json methods of the Response object. Note that headers will not be serialized, unless explicitly included via filterSerializedResponseHeaders
During hydration, the response will be read from the HTML, guaranteeing consistency and preventing an additional network request.

You can learn more about making credentialed requests with cookies here
fetch }) {
	// ...
}

import type { type PageLoad = (event: LoadEvent<RouteParams, Record<string, any> | null, Record<string, any>, string | null>) => MaybePromise<void | Record<string, any>>PageLoad } from './$types';

export const const load: PageLoadload: type PageLoad = (event: LoadEvent<RouteParams, Record<string, any> | null, Record<string, any>, string | null>) => MaybePromise<void | Record<string, any>>PageLoad = async ({ params: RouteParams
The parameters of the current page - e.g. for a route like /blog/[slug], a { slug: string } object
params, 
fetch: {
    (input: RequestInfo | URL, init?: RequestInit): Promise<Response>;
    (input: string | URL | globalThis.Request, init?: RequestInit): Promise<Response>;
}
fetch is equivalent to the native fetch web API, with a few additional features:

It can be used to make credentialed requests on the server, as it inherits the cookie and authorization headers for the page request.
It can make relative requests on the server (ordinarily, fetch requires a URL with an origin when used in a server context).
Internal requests (e.g. for +server.js routes) go directly to the handler function when running on the server, without the overhead of an HTTP call.
During server-side rendering, the response will be captured and inlined into the rendered HTML by hooking into the text and json methods of the Response object. Note that headers will not be serialized, unless explicitly included via filterSerializedResponseHeaders
During hydration, the response will be read from the HTML, guaranteeing consistency and preventing an additional network request.

You can learn more about making credentialed requests with cookies here
fetch }) => {
	// ...
};

<script>
	/** @type {import('./$types').PageProps} */
	let { data, form } = $props();
</script>

<script lang="ts">
	import type { PageProps } from './$types';

	let { data, form }: PageProps = $props();
</script>

{
	"compilerOptions": {
		"paths": {
			"$lib": ["../src/lib"],
			"$lib/*": ["../src/lib/*"]
		},
		"rootDirs": ["..", "./types"]
	},
	"include": [
		"ambient.d.ts",
		"non-ambient.d.ts",
		"./types/**/$types.d.ts",
		"../vite.config.js",
		"../vite.config.ts",
		"../src/**/*.js",
		"../src/**/*.ts",
		"../src/**/*.svelte",
		"../tests/**/*.js",
		"../tests/**/*.ts",
		"../tests/**/*.svelte"
	],
	"exclude": [
		"../node_modules/**",
		"../src/service-worker.js",
		"../src/service-worker/**/*.js",
		"../src/service-worker.ts",
		"../src/service-worker/**/*.ts",
		"../src/service-worker.d.ts",
		"../src/service-worker/**/*.d.ts"
	]
}

{
	"compilerOptions": {
		// this ensures that types are explicitly
		// imported with `import type`, which is
		// necessary as Svelte/Vite cannot
		// otherwise compile components correctly
		"verbatimModuleSyntax": true,

		// Vite compiles one TypeScript module
		// at a time, rather than compiling
		// the entire module graph
		"isolatedModules": true,

		// Tell TS it's used only for type-checking
		"noEmit": true,

		// This ensures both `vite build`
		// and `svelte-package` work correctly
		"lib": ["esnext", "DOM", "DOM.Iterable"],
		"moduleResolution": "bundler",
		"module": "esnext",
		"target": "esnext"
	}
}