> For the complete documentation index, see [llms.txt](https://docs.millimetric.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.millimetric.ai/sdks/frameworks.md).

# Framework recipes

Drop-in setup for React, Next.js, Vue, Svelte, and other JS frameworks.

The browser SDK (`@millimetric/track`) is framework-agnostic — it's just `init`, `track`, `identify`, `page`, `flush`. This page collects the small, copy-paste-ready integrations for the frameworks people actually use.

If your framework isn't listed, the [pure-JS browser snippet](/sdks/browser.md#a-drop-in-script-snippet--for-static-sites-webflow-framer-marketing-pages) Just Works on any HTML page.

## Sub-recipes

* [React](/sdks/frameworks/react.md)
* [Next.js](/sdks/frameworks/nextjs.md)
* [Vue](/sdks/frameworks/vue.md)
* [Svelte / SvelteKit](/sdks/frameworks/svelte.md)

## Common pattern across all of them

Three things, in order:

1. **Init once** — at the top of your app, with your `pk_*` key.
2. **Identify on auth** — when you know who the visitor is.
3. **Track on intent** — buttons, conversions, the things you'd put in a funnel.

Auto-pageviews (including SPA navigations) are on by default; you usually don't have to call `page()` yourself.

## Where to put the key

| Framework               | Env var name (suggested) | Read at                                               |
| ----------------------- | ------------------------ | ----------------------------------------------------- |
| Vite (React/Vue/Svelte) | `VITE_AOA_KEY`           | `import.meta.env.VITE_AOA_KEY`                        |
| Next.js                 | `NEXT_PUBLIC_AOA_KEY`    | `process.env.NEXT_PUBLIC_AOA_KEY`                     |
| Nuxt                    | `NUXT_PUBLIC_AOA_KEY`    | `useRuntimeConfig().public.aoaKey`                    |
| SvelteKit               | `PUBLIC_AOA_KEY`         | `import { PUBLIC_AOA_KEY } from "$env/static/public"` |

The `pk_*` key is browser-safe — it's origin-allowlisted on the server. Never expose `sk_*` or `rk_*` to the browser.

## Anti-patterns

* **Calling `init()` in a render function.** Init is idempotent but inits-per-render is wasteful. Wrap in `useEffect` (React) / `onMount` (Svelte) / `mounted()` (Vue).
* **Tracking inside `useEffect` cleanup.** The cleanup runs on unmount and on every re-render — easy to over-track. Track on the user action (`onClick`), not on the effect lifecycle.
* **Calling `flush()` synchronously in render.** It returns a promise; awaiting it in render breaks SSR.
* **Setting `user_id` from your URL.** Use `identify(user.id)` once after auth resolves; don't pass `user_id` per-call.


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