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The Fungies JavaScript SDK provides a programmatic way to open checkout experiences in your web application.

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Installation

npm install @fungies/fungies-js

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Initialization

import { Fungies } from "@fungies/fungies-js";

// Initialize the SDK
Fungies.Initialize({
  enableDataAttributes: true, // default: true
});

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Opening Checkout

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Overlay Mode

Opens checkout in a full-screen modal overlay: 
Fungies.Checkout.open({
  checkoutUrl: "https://yourstore.fungies.io/checkout-element/your-checkout-id",
  settings: {
    mode: "overlay",
  },
});

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Embed Mode

Renders checkout inside a target DOM element: 
Fungies.Checkout.open({
  checkoutUrl: "https://yourstore.fungies.io/checkout-element/your-checkout-id",
  settings: {
    mode: "embed",
    frameTarget: "checkout-container", // ID of the target element
  },
});

<div id="checkout-container"></div>

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Checkout Options

OptionTypeDescription
checkoutUrlstringRequired. The checkout URL from your Fungies dashboard
settings.mode"overlay" | "embed"Display mode for the checkout
settings.frameTargetstringDOM element ID for embed mode
customerEmailstringCustomer email (deprecated, use billingData.email)
billingDataobjectPrefilled billing information (see below)
discountCodestringDiscount code to apply
quantitynumberProduct quantity
itemsarrayItems for multi-product checkout
customFieldsobjectCustom field values

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Billing Data Object

Prefill customer billing information: 
Fungies.Checkout.open({
  checkoutUrl: "...",
  settings: { mode: "overlay" },
  billingData: {
    email: "customer@example.com",
    firstName: "John",
    lastName: "Doe",
    country: "US", // ISO 3166-1 alpha-2 code
    state: "CA", // State/province code
    city: "Los Angeles",
    zipCode: "90001",
  },
});
FieldTypeDescription
emailstringCustomer email address
firstNamestringCustomer first name
lastNamestringCustomer last name
countrystringCountry code (ISO 3166-1 alpha-2, e.g., US, GB, PL)
statestringState or province
citystringCity name
zipCodestringPostal/ZIP code

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Multi-Product Checkout

Specify quantities for multiple offers: 
Fungies.Checkout.open({
  checkoutUrl: "...",
  settings: { mode: "overlay" },
  items: [
    { offerId: "offer-id-1", quantity: 2 },
    { offerId: "offer-id-2", quantity: 1 },
  ],
});

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Custom Fields

Pass custom field values to the checkout: 
Fungies.Checkout.open({
  checkoutUrl: "...",
  settings: { mode: "overlay" },
  customFields: {
    user_id: "usr_123",
    server_region: "US-West",
  },
});

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Closing Checkout

Programmatically close the checkout: 
Fungies.Checkout.close();

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Listening to checkout events

The SDK listens for messages from the checkout iframe and dispatches DOM events on document. This happens automatically when you call Fungies.Initialize() or use the data-auto-init script attribute — no extra setup is required. Use these events to run your own logic after a purchase (redirect to a thank-you page, refresh entitlements, show a confirmation modal, etc.).
EventWhen it fires
fungies:checkout:completeThe customer completed checkout successfully
fungies:checkout:closeThe checkout was closed (by the customer or after completion)
Import event name constants from the package (recommended): 
import { DOM_CHECKOUT_EVENTS, Fungies } from "@fungies/fungies-js";

Fungies.Initialize();

document.addEventListener(DOM_CHECKOUT_EVENTS.COMPLETE, () => {
  window.location.href = "/thank-you";
});

document.addEventListener(DOM_CHECKOUT_EVENTS.CLOSE, () => {
  console.log("Checkout closed");
});
With the CDN script tag, register listeners after the SDK loads: 
<script
  src="https://cdn.jsdelivr.net/npm/@fungies/fungies-js@latest"
  defer
  data-auto-init
></script>
<script>
  document.addEventListener("fungies:checkout:complete", () => {
    window.location.href = "/thank-you";
  });
</script>
In React, attach listeners in a useEffect and remove them on unmount: 
import { useEffect } from "react";
import { DOM_CHECKOUT_EVENTS, Fungies } from "@fungies/fungies-js";

function App() {
  useEffect(() => {
    Fungies.Initialize();

    const onComplete = () => {
      window.location.href = "/thank-you";
    };

    document.addEventListener(DOM_CHECKOUT_EVENTS.COMPLETE, onComplete);
    return () => {
      document.removeEventListener(DOM_CHECKOUT_EVENTS.COMPLETE, onComplete);
    };
  }, []);

  return (
    <button
      onClick={() =>
        Fungies.Checkout.open({
          checkoutUrl:
            "https://yourstore.fungies.io/checkout-element/your-checkout-id",
          settings: { mode: "overlay" },
        })
      }
    >
      Buy
    </button>
  );
}

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DOM Scanning

If you dynamically add checkout buttons after page load, trigger a manual scan: 
Fungies.ScanDOM();

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Complete Example

import { Fungies } from "@fungies/fungies-js";

// Initialize
Fungies.Initialize();

// Open checkout with all options
document.getElementById("buy-button").addEventListener("click", () => {
  Fungies.Checkout.open({
    checkoutUrl: "https://yourstore.fungies.io/checkout-element/abc123",
    settings: {
      mode: "overlay",
    },
    billingData: {
      email: currentUser.email,
      firstName: currentUser.firstName,
      lastName: currentUser.lastName,
      country: currentUser.country,
    },
    discountCode: "SUMMER20",
    quantity: 1,
    customFields: {
      user_id: currentUser.id,
    },
  });
});