Service workers

if ('serviceWorker' in var navigator: Navigator
The Window.navigator read-only property returns a reference to the Navigator object, which has methods and properties about the application running the script.
MDN Reference
navigator) {
	function addEventListener<"load">(type: "load", listener: (this: Window, ev: Event) => any, options?: boolean | AddEventListenerOptions): void (+1 overload)addEventListener('load', function () {
		var navigator: Navigator
The Window.navigator read-only property returns a reference to the Navigator object, which has methods and properties about the application running the script.
MDN Reference
navigator.Navigator.serviceWorker: ServiceWorkerContainer
The serviceWorker read-only property of the Navigator interface returns the ServiceWorkerContainer object for the associated document, which provides access to registration, removal, upgrade, and communication with the ServiceWorker.
Available only in secure contexts.
MDN Reference
serviceWorker.ServiceWorkerContainer.register(scriptURL: string | URL, options?: RegistrationOptions): Promise<ServiceWorkerRegistration>
The register() method of the ServiceWorkerContainer interface creates or updates a ServiceWorkerRegistration for the given scope.
MDN Reference
register('./path/to/service-worker.js');
	});
}

// Disables access to DOM typings like `HTMLElement` which are not available
// inside a service worker and instantiates the correct globals
/// <reference no-default-lib="true"/>
/// <reference lib="esnext" />
/// <reference lib="webworker" />

// Ensures that the `$service-worker` import has proper type definitions
/// <reference types="@sveltejs/kit" />

// Only necessary if you have an import from `$env/static/public`
/// <reference types="../.svelte-kit/ambient.d.ts" />

import { const build: string[]
An array of URL strings representing the files generated by Vite, suitable for caching with cache.addAll(build).
During development, this is an empty array.
referencebuild, const files: string[]
An array of URL strings representing the files in your static directory, or whatever directory is specified by config.kit.files.assets. You can customize which files are included from static directory using config.kit.serviceWorker.files
referencefiles, const version: string
See config.kit.version. It's useful for generating unique cache names inside your service worker, so that a later deployment of your app can invalidate old caches.
referenceversion } from '$service-worker';

// This gives `self` the correct types
const const self: ServiceWorkerGlobalScopeself = /** @type {ServiceWorkerGlobalScope} */ (/** @type {unknown} */ (module globalThisglobalThis.var self: Window & typeof globalThis
The Window.self read-only property returns the window itself, as a WindowProxy. It can be used with dot notation on a window object (that is, window.self) or standalone (self). The advantage of the standalone notation is that a similar notation exists for non-window contexts, such as in Web Workers. By using self, you can refer to the global scope in a way that will work not only in a window context (self will resolve to window.self) but also in a worker context (self will then resolve to WorkerGlobalScope.self).
MDN Reference
The self read-only property of the WorkerGlobalScope interface returns a reference to the WorkerGlobalScope itself. Most of the time it is a specific scope like DedicatedWorkerGlobalScope, SharedWorkerGlobalScope, or ServiceWorkerGlobalScope.
MDN Reference
self));

// Create a unique cache name for this deployment
const const CACHE: stringCACHE = `cache-${const version: string
See config.kit.version. It's useful for generating unique cache names inside your service worker, so that a later deployment of your app can invalidate old caches.
referenceversion}`;

const const ASSETS: string[]ASSETS = [
	...const build: string[]
An array of URL strings representing the files generated by Vite, suitable for caching with cache.addAll(build).
During development, this is an empty array.
referencebuild, // the app itself
	...const files: string[]
An array of URL strings representing the files in your static directory, or whatever directory is specified by config.kit.files.assets. You can customize which files are included from static directory using config.kit.serviceWorker.files
referencefiles  // everything in `static`
];

const self: ServiceWorkerGlobalScopeself.ServiceWorkerGlobalScope.addEventListener<"install">(type: "install", listener: (this: ServiceWorkerGlobalScope, ev: ExtendableEvent) => any, options?: boolean | AddEventListenerOptions): void (+1 overload)
The addEventListener() method of the EventTarget interface sets up a function that will be called whenever the specified event is delivered to the target.
MDN Reference
addEventListener('install', (event: ExtendableEventevent) => {
	// Create a new cache and add all files to it
	async function function (local function) addFilesToCache(): Promise<void>addFilesToCache() {
		const const cache: Cachecache = await var caches: CacheStorage
Available only in secure contexts.
MDN Reference
caches.CacheStorage.open(cacheName: string): Promise<Cache> (+1 overload)
The open() method of the CacheStorage interface returns a Promise that resolves to the Cache object matching the cacheName.
MDN Reference
open(const CACHE: stringCACHE);
		await const cache: Cachecache.Cache.addAll(requests: Iterable<RequestInfo>): Promise<void> (+3 overloads)
The addAll() method of the Cache interface takes an array of URLs, retrieves them, and adds the resulting response objects to the given cache. The request objects created during retrieval become keys to the stored response operations.
MDN Reference
addAll(const ASSETS: string[]ASSETS);
	}

	event: ExtendableEventevent.ExtendableEvent.waitUntil(f: Promise<any>): void
The ExtendableEvent.waitUntil() method tells the event dispatcher that work is ongoing. It can also be used to detect whether that work was successful. In service workers, waitUntil() tells the browser that work is ongoing until the promise settles, and it shouldn't terminate the service worker if it wants that work to complete.
MDN Reference
waitUntil(function (local function) addFilesToCache(): Promise<void>addFilesToCache());
});

const self: ServiceWorkerGlobalScopeself.ServiceWorkerGlobalScope.addEventListener<"activate">(type: "activate", listener: (this: ServiceWorkerGlobalScope, ev: ExtendableEvent) => any, options?: boolean | AddEventListenerOptions): void (+1 overload)
The addEventListener() method of the EventTarget interface sets up a function that will be called whenever the specified event is delivered to the target.
MDN Reference
addEventListener('activate', (event: ExtendableEventevent) => {
	// Remove previous cached data from disk
	async function function (local function) deleteOldCaches(): Promise<void>deleteOldCaches() {
		for (const const key: stringkey of await var caches: CacheStorage
Available only in secure contexts.
MDN Reference
caches.CacheStorage.keys(): Promise<string[]> (+1 overload)
The keys() method of the CacheStorage interface returns a Promise that will resolve with an array containing strings corresponding to all of the named Cache objects tracked by the CacheStorage object in the order they were created. Use this method to iterate over a list of all Cache objects.
MDN Reference
keys()) {
			if (const key: stringkey !== const CACHE: stringCACHE) await var caches: CacheStorage
Available only in secure contexts.
MDN Reference
caches.CacheStorage.delete(cacheName: string): Promise<boolean> (+1 overload)
The delete() method of the CacheStorage interface finds the Cache object matching the cacheName, and if found, deletes the Cache object and returns a Promise that resolves to true. If no Cache object is found, it resolves to false.
MDN Reference
delete(const key: stringkey);
		}
	}

	event: ExtendableEventevent.ExtendableEvent.waitUntil(f: Promise<any>): void
The ExtendableEvent.waitUntil() method tells the event dispatcher that work is ongoing. It can also be used to detect whether that work was successful. In service workers, waitUntil() tells the browser that work is ongoing until the promise settles, and it shouldn't terminate the service worker if it wants that work to complete.
MDN Reference
waitUntil(function (local function) deleteOldCaches(): Promise<void>deleteOldCaches());
});

const self: ServiceWorkerGlobalScopeself.ServiceWorkerGlobalScope.addEventListener<"fetch">(type: "fetch", listener: (this: ServiceWorkerGlobalScope, ev: FetchEvent) => any, options?: boolean | AddEventListenerOptions): void (+1 overload)
The addEventListener() method of the EventTarget interface sets up a function that will be called whenever the specified event is delivered to the target.
MDN Reference
addEventListener('fetch', (event: FetchEventevent) => {
	// ignore POST requests etc
	if (event: FetchEventevent.FetchEvent.request: Request
The request read-only property of the FetchEvent interface returns the Request that triggered the event handler.
MDN Reference
request.Request.method: string
The method read-only property of the Request interface contains the request's method (GET, POST, etc.)
MDN Reference
method !== 'GET') return;

	async function function (local function) respond(): Promise<Response>respond() {
		const const url: URLurl = new var URL: new (url: string | URL, base?: string | URL) => URL
The URL interface is used to parse, construct, normalize, and encode URLs. It works by providing properties which allow you to easily read and modify the components of a URL.
MDN Reference
URL class is a global reference for import { URL } from 'url'
https://nodejs.org/api/url.html#the-whatwg-url-api
@since
v10.0.0URL(event: FetchEventevent.FetchEvent.request: Request
The request read-only property of the FetchEvent interface returns the Request that triggered the event handler.
MDN Reference
request.Request.url: string
The url read-only property of the Request interface contains the URL of the request.
MDN Reference
url);
		const const cache: Cachecache = await var caches: CacheStorage
Available only in secure contexts.
MDN Reference
caches.CacheStorage.open(cacheName: string): Promise<Cache> (+1 overload)
The open() method of the CacheStorage interface returns a Promise that resolves to the Cache object matching the cacheName.
MDN Reference
open(const CACHE: stringCACHE);

		// `build`/`files` can always be served from the cache
		if (const ASSETS: string[]ASSETS.Array<string>.includes(searchElement: string, fromIndex?: number): boolean
Determines whether an array includes a certain element, returning true or false as appropriate.
@param
searchElement The element to search for.
@param
fromIndex The position in this array at which to begin searching for searchElement.includes(const url: URLurl.URL.pathname: string
The pathname property of the URL interface represents a location in a hierarchical structure. It is a string constructed from a list of path segments, each of which is prefixed by a / character.
MDN Reference
pathname)) {
			const const response: Response | undefinedresponse = await const cache: Cachecache.Cache.match(request: RequestInfo | URL, options?: CacheQueryOptions): Promise<Response | undefined> (+1 overload)
The match() method of the Cache interface returns a Promise that resolves to the Response associated with the first matching request in the Cache object. If no match is found, the Promise resolves to undefined.
MDN Reference
match(const url: URLurl.URL.pathname: string
The pathname property of the URL interface represents a location in a hierarchical structure. It is a string constructed from a list of path segments, each of which is prefixed by a / character.
MDN Reference
pathname);

			if (const response: Response | undefinedresponse) {
				return const response: Responseresponse;
			}
		}

		// for everything else, try the network first, but
		// fall back to the cache if we're offline
		try {
			const const response: Responseresponse = await function fetch(input: string | URL | Request, init?: RequestInit): Promise<Response> (+2 overloads)
MDN Reference
fetch(event: FetchEventevent.FetchEvent.request: Request
The request read-only property of the FetchEvent interface returns the Request that triggered the event handler.
MDN Reference
request);

			// if we're offline, fetch can return a value that is not a Response
			// instead of throwing - and we can't pass this non-Response to respondWith
			if (!(const response: Responseresponse instanceof 
var Response: {
    new (body?: BodyInit | null, init?: ResponseInit): Response;
    prototype: Response;
    error(): Response;
    json(data: any, init?: ResponseInit): Response;
    redirect(url: string | URL, status?: number): Response;
}
The Response interface of the Fetch API represents the response to a request.
MDN Reference
Response)) {
				throw new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)Error('invalid response from fetch');
			}

			if (const response: Responseresponse.Response.status: number
The status read-only property of the Response interface contains the HTTP status codes of the response.
MDN Reference
status === 200 && !const response: Responseresponse.Response.headers: Headers
The headers read-only property of the Response interface contains the Headers object associated with the response.
MDN Reference
headers.Headers.get(name: string): string | null (+1 overload)
The get() method of the Headers interface returns a byte string of all the values of a header within a Headers object with a given name. If the requested header doesn't exist in the Headers object, it returns null.
MDN Reference
get('cache-control')?.String.includes(searchString: string, position?: number): boolean
Returns true if searchString appears as a substring of the result of converting this
object to a String, at one or more positions that are
greater than or equal to position; otherwise, returns false.
@param
searchString search string
@param
position If position is undefined, 0 is assumed, so as to search all of the String.includes('no-store')) {
				const cache: Cachecache.Cache.put(request: RequestInfo | URL, response: Response): Promise<void> (+1 overload)
The put() method of the Cache interface allows key/value pairs to be added to the current Cache object.
MDN Reference
put(event: FetchEventevent.FetchEvent.request: Request
The request read-only property of the FetchEvent interface returns the Request that triggered the event handler.
MDN Reference
request, const response: Responseresponse.Response.clone(): Response (+1 overload)
The clone() method of the Response interface creates a clone of a response object, identical in every way, but stored in a different variable.
MDN Reference
clone());
			}

			return const response: Responseresponse;
		} catch (function (local var) err: unknownerr) {
			const const response: Response | undefinedresponse = await const cache: Cachecache.Cache.match(request: RequestInfo | URL, options?: CacheQueryOptions): Promise<Response | undefined> (+1 overload)
The match() method of the Cache interface returns a Promise that resolves to the Response associated with the first matching request in the Cache object. If no match is found, the Promise resolves to undefined.
MDN Reference
match(event: FetchEventevent.FetchEvent.request: Request
The request read-only property of the FetchEvent interface returns the Request that triggered the event handler.
MDN Reference
request);

			if (const response: Response | undefinedresponse) {
				return const response: Responseresponse;
			}

			// if there's no cache, then just error out
			// as there is nothing we can do to respond to this request
			throw function (local var) err: unknownerr;
		}
	}

	event: FetchEventevent.FetchEvent.respondWith(r: Response | PromiseLike<Response>): void
The respondWith() method of FetchEvent prevents the browser's default fetch handling, and allows you to provide a promise for a Response yourself.
MDN Reference
respondWith(function (local function) respond(): Promise<Response>respond());
});

// Disables access to DOM typings like `HTMLElement` which are not available
// inside a service worker and instantiates the correct globals
/// <reference no-default-lib="true"/>
/// <reference lib="esnext" />
/// <reference lib="webworker" />

// Ensures that the `$service-worker` import has proper type definitions
/// <reference types="@sveltejs/kit" />

// Only necessary if you have an import from `$env/static/public`
/// <reference types="../.svelte-kit/ambient.d.ts" />

import { const build: string[]
An array of URL strings representing the files generated by Vite, suitable for caching with cache.addAll(build).
During development, this is an empty array.
referencebuild, const files: string[]
An array of URL strings representing the files in your static directory, or whatever directory is specified by config.kit.files.assets. You can customize which files are included from static directory using config.kit.serviceWorker.files
referencefiles, const version: string
See config.kit.version. It's useful for generating unique cache names inside your service worker, so that a later deployment of your app can invalidate old caches.
referenceversion } from '$service-worker';

// This gives `self` the correct types
const const self: ServiceWorkerGlobalScopeself = module globalThisglobalThis.var self: Window & typeof globalThis
The Window.self read-only property returns the window itself, as a WindowProxy. It can be used with dot notation on a window object (that is, window.self) or standalone (self). The advantage of the standalone notation is that a similar notation exists for non-window contexts, such as in Web Workers. By using self, you can refer to the global scope in a way that will work not only in a window context (self will resolve to window.self) but also in a worker context (self will then resolve to WorkerGlobalScope.self).
MDN Reference
The self read-only property of the WorkerGlobalScope interface returns a reference to the WorkerGlobalScope itself. Most of the time it is a specific scope like DedicatedWorkerGlobalScope, SharedWorkerGlobalScope, or ServiceWorkerGlobalScope.
MDN Reference
self as unknown as ServiceWorkerGlobalScope;

// Create a unique cache name for this deployment
const const CACHE: stringCACHE = `cache-${const version: string
See config.kit.version. It's useful for generating unique cache names inside your service worker, so that a later deployment of your app can invalidate old caches.
referenceversion}`;

const const ASSETS: string[]ASSETS = [
	...const build: string[]
An array of URL strings representing the files generated by Vite, suitable for caching with cache.addAll(build).
During development, this is an empty array.
referencebuild, // the app itself
	...const files: string[]
An array of URL strings representing the files in your static directory, or whatever directory is specified by config.kit.files.assets. You can customize which files are included from static directory using config.kit.serviceWorker.files
referencefiles  // everything in `static`
];

const self: ServiceWorkerGlobalScopeself.ServiceWorkerGlobalScope.addEventListener<"install">(type: "install", listener: (this: ServiceWorkerGlobalScope, ev: ExtendableEvent) => any, options?: boolean | AddEventListenerOptions): void (+1 overload)
The addEventListener() method of the EventTarget interface sets up a function that will be called whenever the specified event is delivered to the target.
MDN Reference
addEventListener('install', (event: ExtendableEventevent) => {
	// Create a new cache and add all files to it
	async function function (local function) addFilesToCache(): Promise<void>addFilesToCache() {
		const const cache: Cachecache = await var caches: CacheStorage
Available only in secure contexts.
MDN Reference
caches.CacheStorage.open(cacheName: string): Promise<Cache> (+1 overload)
The open() method of the CacheStorage interface returns a Promise that resolves to the Cache object matching the cacheName.
MDN Reference
open(const CACHE: stringCACHE);
		await const cache: Cachecache.Cache.addAll(requests: Iterable<RequestInfo>): Promise<void> (+3 overloads)
The addAll() method of the Cache interface takes an array of URLs, retrieves them, and adds the resulting response objects to the given cache. The request objects created during retrieval become keys to the stored response operations.
MDN Reference
addAll(const ASSETS: string[]ASSETS);
	}

	event: ExtendableEventevent.ExtendableEvent.waitUntil(f: Promise<any>): void
The ExtendableEvent.waitUntil() method tells the event dispatcher that work is ongoing. It can also be used to detect whether that work was successful. In service workers, waitUntil() tells the browser that work is ongoing until the promise settles, and it shouldn't terminate the service worker if it wants that work to complete.
MDN Reference
waitUntil(function (local function) addFilesToCache(): Promise<void>addFilesToCache());
});

const self: ServiceWorkerGlobalScopeself.ServiceWorkerGlobalScope.addEventListener<"activate">(type: "activate", listener: (this: ServiceWorkerGlobalScope, ev: ExtendableEvent) => any, options?: boolean | AddEventListenerOptions): void (+1 overload)
The addEventListener() method of the EventTarget interface sets up a function that will be called whenever the specified event is delivered to the target.
MDN Reference
addEventListener('activate', (event: ExtendableEventevent) => {
	// Remove previous cached data from disk
	async function function (local function) deleteOldCaches(): Promise<void>deleteOldCaches() {
		for (const const key: stringkey of await var caches: CacheStorage
Available only in secure contexts.
MDN Reference
caches.CacheStorage.keys(): Promise<string[]> (+1 overload)
The keys() method of the CacheStorage interface returns a Promise that will resolve with an array containing strings corresponding to all of the named Cache objects tracked by the CacheStorage object in the order they were created. Use this method to iterate over a list of all Cache objects.
MDN Reference
keys()) {
			if (const key: stringkey !== const CACHE: stringCACHE) await var caches: CacheStorage
Available only in secure contexts.
MDN Reference
caches.CacheStorage.delete(cacheName: string): Promise<boolean> (+1 overload)
The delete() method of the CacheStorage interface finds the Cache object matching the cacheName, and if found, deletes the Cache object and returns a Promise that resolves to true. If no Cache object is found, it resolves to false.
MDN Reference
delete(const key: stringkey);
		}
	}

	event: ExtendableEventevent.ExtendableEvent.waitUntil(f: Promise<any>): void
The ExtendableEvent.waitUntil() method tells the event dispatcher that work is ongoing. It can also be used to detect whether that work was successful. In service workers, waitUntil() tells the browser that work is ongoing until the promise settles, and it shouldn't terminate the service worker if it wants that work to complete.
MDN Reference
waitUntil(function (local function) deleteOldCaches(): Promise<void>deleteOldCaches());
});

const self: ServiceWorkerGlobalScopeself.ServiceWorkerGlobalScope.addEventListener<"fetch">(type: "fetch", listener: (this: ServiceWorkerGlobalScope, ev: FetchEvent) => any, options?: boolean | AddEventListenerOptions): void (+1 overload)
The addEventListener() method of the EventTarget interface sets up a function that will be called whenever the specified event is delivered to the target.
MDN Reference
addEventListener('fetch', (event: FetchEventevent) => {
	// ignore POST requests etc
	if (event: FetchEventevent.FetchEvent.request: Request
The request read-only property of the FetchEvent interface returns the Request that triggered the event handler.
MDN Reference
request.Request.method: string
The method read-only property of the Request interface contains the request's method (GET, POST, etc.)
MDN Reference
method !== 'GET') return;

	async function function (local function) respond(): Promise<Response>respond() {
		const const url: URLurl = new var URL: new (url: string | URL, base?: string | URL) => URL
The URL interface is used to parse, construct, normalize, and encode URLs. It works by providing properties which allow you to easily read and modify the components of a URL.
MDN Reference
URL class is a global reference for import { URL } from 'url'
https://nodejs.org/api/url.html#the-whatwg-url-api
@since
v10.0.0URL(event: FetchEventevent.FetchEvent.request: Request
The request read-only property of the FetchEvent interface returns the Request that triggered the event handler.
MDN Reference
request.Request.url: string
The url read-only property of the Request interface contains the URL of the request.
MDN Reference
url);
		const const cache: Cachecache = await var caches: CacheStorage
Available only in secure contexts.
MDN Reference
caches.CacheStorage.open(cacheName: string): Promise<Cache> (+1 overload)
The open() method of the CacheStorage interface returns a Promise that resolves to the Cache object matching the cacheName.
MDN Reference
open(const CACHE: stringCACHE);

		// `build`/`files` can always be served from the cache
		if (const ASSETS: string[]ASSETS.Array<string>.includes(searchElement: string, fromIndex?: number): boolean
Determines whether an array includes a certain element, returning true or false as appropriate.
@param
searchElement The element to search for.
@param
fromIndex The position in this array at which to begin searching for searchElement.includes(const url: URLurl.URL.pathname: string
The pathname property of the URL interface represents a location in a hierarchical structure. It is a string constructed from a list of path segments, each of which is prefixed by a / character.
MDN Reference
pathname)) {
			const const response: Response | undefinedresponse = await const cache: Cachecache.Cache.match(request: RequestInfo | URL, options?: CacheQueryOptions): Promise<Response | undefined> (+1 overload)
The match() method of the Cache interface returns a Promise that resolves to the Response associated with the first matching request in the Cache object. If no match is found, the Promise resolves to undefined.
MDN Reference
match(const url: URLurl.URL.pathname: string
The pathname property of the URL interface represents a location in a hierarchical structure. It is a string constructed from a list of path segments, each of which is prefixed by a / character.
MDN Reference
pathname);

			if (const response: Response | undefinedresponse) {
				return const response: Responseresponse;
			}
		}

		// for everything else, try the network first, but
		// fall back to the cache if we're offline
		try {
			const const response: Responseresponse = await function fetch(input: string | URL | Request, init?: RequestInit): Promise<Response> (+2 overloads)
MDN Reference
fetch(event: FetchEventevent.FetchEvent.request: Request
The request read-only property of the FetchEvent interface returns the Request that triggered the event handler.
MDN Reference
request);

			// if we're offline, fetch can return a value that is not a Response
			// instead of throwing - and we can't pass this non-Response to respondWith
			if (!(const response: Responseresponse instanceof 
var Response: {
    new (body?: BodyInit | null, init?: ResponseInit): Response;
    prototype: Response;
    error(): Response;
    json(data: any, init?: ResponseInit): Response;
    redirect(url: string | URL, status?: number): Response;
}
The Response interface of the Fetch API represents the response to a request.
MDN Reference
Response)) {
				throw new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)Error('invalid response from fetch');
			}

			if (const response: Responseresponse.Response.status: number
The status read-only property of the Response interface contains the HTTP status codes of the response.
MDN Reference
status === 200 && !const response: Responseresponse.Response.headers: Headers
The headers read-only property of the Response interface contains the Headers object associated with the response.
MDN Reference
headers.Headers.get(name: string): string | null (+1 overload)
The get() method of the Headers interface returns a byte string of all the values of a header within a Headers object with a given name. If the requested header doesn't exist in the Headers object, it returns null.
MDN Reference
get('cache-control')?.String.includes(searchString: string, position?: number): boolean
Returns true if searchString appears as a substring of the result of converting this
object to a String, at one or more positions that are
greater than or equal to position; otherwise, returns false.
@param
searchString search string
@param
position If position is undefined, 0 is assumed, so as to search all of the String.includes('no-store')) {
				const cache: Cachecache.Cache.put(request: RequestInfo | URL, response: Response): Promise<void> (+1 overload)
The put() method of the Cache interface allows key/value pairs to be added to the current Cache object.
MDN Reference
put(event: FetchEventevent.FetchEvent.request: Request
The request read-only property of the FetchEvent interface returns the Request that triggered the event handler.
MDN Reference
request, const response: Responseresponse.Response.clone(): Response (+1 overload)
The clone() method of the Response interface creates a clone of a response object, identical in every way, but stored in a different variable.
MDN Reference
clone());
			}

			return const response: Responseresponse;
		} catch (function (local var) err: unknownerr) {
			const const response: Response | undefinedresponse = await const cache: Cachecache.Cache.match(request: RequestInfo | URL, options?: CacheQueryOptions): Promise<Response | undefined> (+1 overload)
The match() method of the Cache interface returns a Promise that resolves to the Response associated with the first matching request in the Cache object. If no match is found, the Promise resolves to undefined.
MDN Reference
match(event: FetchEventevent.FetchEvent.request: Request
The request read-only property of the FetchEvent interface returns the Request that triggered the event handler.
MDN Reference
request);

			if (const response: Response | undefinedresponse) {
				return const response: Responseresponse;
			}

			// if there's no cache, then just error out
			// as there is nothing we can do to respond to this request
			throw function (local var) err: unknownerr;
		}
	}

	event: FetchEventevent.FetchEvent.respondWith(r: Response | PromiseLike<Response>): void
The respondWith() method of FetchEvent prevents the browser's default fetch handling, and allows you to provide a promise for a Response yourself.
MDN Reference
respondWith(function (local function) respond(): Promise<Response>respond());
});

import { import dev
referencedev } from '$app/environment';

var navigator: Navigator
The Window.navigator read-only property returns a reference to the Navigator object, which has methods and properties about the application running the script.
MDN Reference
navigator.Navigator.serviceWorker: ServiceWorkerContainer
The serviceWorker read-only property of the Navigator interface returns the ServiceWorkerContainer object for the associated document, which provides access to registration, removal, upgrade, and communication with the ServiceWorker.
Available only in secure contexts.
MDN Reference
serviceWorker.ServiceWorkerContainer.register(scriptURL: string | URL, options?: RegistrationOptions): Promise<ServiceWorkerRegistration>
The register() method of the ServiceWorkerContainer interface creates or updates a ServiceWorkerRegistration for the given scope.
MDN Reference
register('/service-worker.js', {
	RegistrationOptions.type?: WorkerType | undefinedtype: import dev
referencedev ? 'module' : 'classic'
});