develop-extension

name	develop-extension
description	Author a new PostHog browser extension, or port a posthog-js v1 extension, against the @posthog/browser-common Client/Extension contract. Use when adding or porting an extension (autocapture, pageview, surveys, replay, exceptions, web-vitals, campaign-params, feature flags, …).

Authoring a browser extension

A browser extension is an opt-in feature that implements Extension and talks to its host SDK exclusively through the single Client adapter passed to setup and shared by extensions on that SDK instance. The contract is designed for extensions shared across browser generations; concrete host adapters and loading integrations remain owned by their SDK packages.

The shape

Prefer a class when porting a posthog-js v1 extension that is already a class. Retaining its method boundaries makes the port easier to review and keeps future fixes comparable with v1.

import type { Client, Extension } from '@posthog/browser-common'

import { MyExtensionToken } from './my-extension-contract'

export interface MyExtensionOptions {
    enabled?: boolean
}

export class MyExtension implements Extension {
     name = 
     :  | 

    () {}

    (: ):  | <> {
        . = client
        .()
    }

    ():  {
        
    }

    ():  {
        
    }

    ():  {
        .()
        . = 
    }
}