Getting started

@fkn/lib gives a browser app access to FKN’s cloud networking, storage, account, and page-automation APIs. Cloud networking and isolated page automation need no extension or account; cloud storage requires a connected account. Install the optional FKN browser extension when your app needs to use the user’s browser, cookies, or logged-in session.

Install

npm install @fkn/lib

Use ESM imports in your app. The package includes TypeScript declarations, and the examples on this site are type-checked against the published release.

Make a cloud request

The explicit cloud.* namespace pins a call to FKN’s hosted backend:

import { 
(alias) namespace cloud
import cloud
cloud } from '@fkn/lib'

const 
const response: Response
response = await 
(alias) namespace cloud
import cloud
cloud.
cloud_d_exports.fetch(input: string | Request | URL, init?: (RequestInit & {
    render?: boolean;
}) | undefined): Promise<Response>
export cloud_d_exports.fetch
fetch('https://example.com/api/catalog')
const 
const data: any
data = await 
const response: Response
response.
Body.json(): Promise<any>
MDN Reference
json()

No account is required. Anonymous cloud use is metered per IP; connecting an account moves metering to that account. See Quota and throttling.

For a request that can use either the extension or cloud, import the root fetch() instead. The exact selection rules are documented under API backends.

Attach a frame with cloud fallback

If the extension is exposed, attachFrame() uses it; otherwise it starts the cloud backend with no install prompt. Pass syncCookies: false when the frame should use an isolated per-attach cloud session instead of the persistent cloud jar.

import { 
const attachFrame: (options: AttachFrameOptions) => Promise<Frame>
attachFrame } from '@fkn/lib'

const 
const iframe: HTMLIFrameElement
iframe = 
var document: Document
window.document returns a reference to the document contained in the window.
MDN Reference
document.
ParentNode.querySelector<"iframe">(selectors: "iframe"): HTMLIFrameElement | null (+4 overloads)
Returns the first element that is a descendant of node that matches selectors.
MDN Reference
querySelector('iframe')!
const 
const frame: Frame
frame = await 
function attachFrame(options: AttachFrameOptions): Promise<Frame>
attachFrame({ 
iframe: HTMLIFrameElement
iframe, 
syncCookies?: boolean | undefined
syncCookies: false })

await 
const frame: Frame
frame.
function goto(url: string, options?: GotoOptions): Promise<void>
goto('https://example.com', { 
waitUntil?: "documentstart" | "load" | undefined
waitUntil: 'load' })
const 
const title: string
title = await 
const frame: Frame
frame.
locator: (selector: string) => Locator
locator('h1').
textContent: (_options?: OperationTimeoutOptions | undefined) => Promise<string>
textContent()

A frame that must use the user’s existing browser session needs the extension backend: pin it with extension.attachFrame(), which waits for exposure and surfaces the install flow when the extension is missing. On the cloud backend the user’s session comes from logging in inside the proxied page itself, and the default cookie mode keeps that login in the persistent cloud jar across attachments.

Detect the extension

The extension announces itself asynchronously to each page. Check for it before showing extension-specific UI:

import { 
const isExtensionExposed: () => boolean
isExtensionExposed, 
const waitForExtensionExposure: (timeout?: number) => Promise<void>
waitForExtensionExposure } from '@fkn/lib'

if (
function isExtensionExposed(): boolean
isExtensionExposed()) {
  
var console: Console
console.
Console.log(...data: any[]): void
The console.log() static method outputs a message to the console.
MDN Reference
log('FKN extension is available')
}

await 
function waitForExtensionExposure(timeout?: number): Promise<void>
waitForExtensionExposure()

waitForExtensionExposure() rejects when the extension is not installed. By default, an extension-required call also opens FKN’s install prompt. Apps with their own absence UI or cloud fallback can suppress that prompt:

import { 
const promptInstall: (reason?: string) => Promise<boolean>
promptInstall, 
const setMissingExtensionHandler: (handler: MissingExtensionHandler | null) => void
setMissingExtensionHandler } from '@fkn/lib'

function setMissingExtensionHandler(handler: MissingExtensionHandler | null): void
setMissingExtensionHandler(null)

// Call this later from your own install button.
await 
function promptInstall(reason?: string): Promise<boolean>
promptInstall()

Use an extension-only capability

Extension APIs are explicit under extension.*. Sensitive operations prompt for per-app consent; severity-0 operations are granted automatically and recorded once per capability and scope during a visit.

import { 
(alias) namespace extension
import extension
extension } from '@fkn/lib'

const 
const response: Response
response = await 
(alias) namespace extension
import extension
extension.
extension_d_exports.fetch(input: RequestInfo | URL, init?: extension.FetchInit): Promise<Response>
export extension_d_exports.fetch
fetch('https://example.com/api/me', {
  
RequestInit.credentials?: RequestCredentials | undefined
A string indicating whether credentials will be sent with the request always, never, or only when sent to a same-origin URL. Sets request's credentials.
credentials: 'include',
  
reason?: string | undefined
reason: 'Load your profile from your existing session',
})

See it run

The guided demo below embeds Wikipedia, restyles it, reads the heading, fills a search, and clicks Search. It uses an isolated cloud session with no install. If the FKN extension is already exposed, it uses the extension instead and asks once for the three sensitive actions.

Guided demo: FKN acting on en.wikipedia.orgOpen in new tab

Continue with API backends for routing behavior or attachFrame() for the complete frame API.