After client-side goto?

onMount runs per navigation to /contact—sufficient for default embed observer too.

Use +page.server.ts actions to POST with ingest secret instead of embed.

Prerendered HTML still runs embed in browser; allowlist production URL.

TypeScript window.MuxForms?

Optional global interface; mount is guarded with optional chaining.

MuxForms on SvelteKit loads embed.js in src/app.html or +layout.svelte, uses onMount in +page.svelte to call MuxForms.mount, and allowlists your deployed origin (Vercel, Netlify, or Cloudflare).

Docs

SvelteKit

SvelteKit client navigations need a fresh mount when users land on /contact without a full reload.

SvelteKit

File	Role
app.html	Global script tag
routes/contact/+page.svelte	Mount target
+page.server.ts	Optional server POST
adapter	Public URL → allowlist

src/routes/contact/+page.svelte

<script lang="ts">
  import { onMount } from "svelte";
  let root: HTMLDivElement;

  onMount(() => {
    if (root) window.MuxForms?.mount(root);
  });
</script>

<h1>Contact</h1>
<div bind:this={root} data-form-id="FORM_UUID"></div>

src/app.html

%sveltekit.body%
<script src="https://www.muxforms.com/embed.js" defer></script>

Common questions

After client-side goto?: onMount runs per navigation to /contact—sufficient for default embed observer too.
Form actions?: Use +page.server.ts actions to POST with ingest secret instead of embed.
Prerender?: Prerendered HTML still runs embed in browser; allowlist production URL.
TypeScript window.MuxForms?: Optional global interface; mount is guarded with optional chaining.

Kit apps, shared inbox.

Server actions optional—embed is the fast path.

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