How to integrate Buttons and RSVP Forms with Next.js

This guide uses the Next.js App Router with React 19. React 19 supports Web Components directly. Use the core add-to-calendar-button package and the <add-to-calendar-button> element.

Step 1: npm installation

npm install add-to-calendar-button

Step 2: Create your component

app/components/event-button.tsx:

'use client';

import 'add-to-calendar-button';

export default function EventButton() {
  return (
    <add-to-calendar-button prokey="prokey-of-your-event"></add-to-calendar-button>
  );
}

Your event data, styles, and RSVP settings remain connected to the PRO app through the prokey.

Import this Client Component into your page:

// app/page.tsx
import EventButton from './components/event-button';

export default function Page() {
  return <EventButton />;
}

The 'use client' directive marks the interactive component. A separate SSR entry can also pre-render a button shell; see below.

Step 3: Add the custom element TypeScript declaration

Register the JSX type once in a declaration file included by your tsconfig.json. JavaScript projects can skip this step.

// src/global.d.ts
import type { AddToCalendarButtonType } from 'add-to-calendar-button';
import type { DetailedHTMLProps, HTMLAttributes } from 'react';

declare module 'react' {
  namespace JSX {
    interface IntrinsicElements {
      'add-to-calendar-button': DetailedHTMLProps<
        Omit<HTMLAttributes<HTMLElement>, keyof AddToCalendarButtonType>,
        HTMLElement
      > & AddToCalendarButtonType;
    }
  }
}

export {};

If compilerOptions.types is set, include react and react-dom alongside its existing entries. For example, preserve vite/client in a Vite project.

Bring your own button

Use atcb_action from the core package in a React click handler to open the button or form as a modal. Pass the trigger element for focus handling.

'use client';

import { atcb_action } from 'add-to-calendar-button';

export default function CustomEventButton() {
  return (
    <button
      onClick={(event) =>
        atcb_action({ prokey: 'prokey-of-your-event' }, event.currentTarget)
      }
    >
      Open event
    </button>
  );
}

Styles and languages

The npm package includes only the default style and English by default. Import every additional style and language selected in the PRO app for your buttons and RSVP forms:

import 'add-to-calendar-button/styles/3d';
import 'add-to-calendar-button/i18n/de';

Place these imports alongside the core import or in a shared setup module.

Alternatively, load styles and languages dynamically from jsDelivr by setting style-source="https://cdn.jsdelivr.net/npm/add-to-calendar-button@3/dist/styles/" on the element. Apply the same strategy to custom triggers; the option is named styleSource in atcb_action.

Optional: Server-side rendering

The package provides a separate SSR entry to pre-render a button shell. Use its asynchronous variant on the server for PRO data. Full interaction and RSVP forms still initialize in the browser. See SSR with PRO and the Button Next.js guide.