### Install XPay SDK via npm

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Use this command to install the SDK package in projects using a bundler.

```bash
npm install @xpayeg/sdk
```

--------------------------------

### Include XPay SDK via CDN

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Use this script tag for non-bundler setups to load the SDK directly in the browser.

```html
<script src="https://checkout.xpay.app/v1/sdk.js"></script>
```

--------------------------------

### Create Checkout Session on Server

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Example Node.js endpoint to create a checkout session and return the clientSecret to the frontend.

```javascript
// Your server (Node.js example)
app.post('/api/create-checkout', async (req, res) => {
  const response = await fetch('https://api.xpay.app/checkout/sessions', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.XPAY_SECRET_KEY}`,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      uiMode: 'custom', // 'custom' for Elements SDK, 'embedded' for drop-in modal, 'hosted' for redirect
      lineItems: [
        {
          priceData: {
            unitAmount: 50000,  // 500.00 EGP in piasters
            currency: 'EGP',
            productData: { name: 'Premium Plan' },
          },
          quantity: 1,
        },
      ],
      afterCompletion: {
        type: 'redirect',
        redirect: {
          // {CHECKOUT_SESSION_ID} is automatically replaced with the actual session ID
          url: 'https://yoursite.com/success?session_id={CHECKOUT_SESSION_ID}',
        },
      },
    }),
  });

  const session = await response.json();
  res.json({ clientSecret: session.clientSecret });
});
```

--------------------------------

### Load XPay SDK

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Load the SDK from the CDN. This should be called at the module level.

```javascript
import { loadXPay } from '@xpayeg/sdk';
const xpay = await loadXPay('pk_test_xxx');
```

--------------------------------

### XPay.checkout()

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Initializes the checkout modal overlay for processing payments.

```APIDOC
## XPay.checkout(options)

### Description
Initializes a checkout session in a modal overlay. Requires a client secret and provides callbacks for completion and closure.

### Parameters
- **clientSecret** (string) - Required - The secret key for the checkout session.
- **mode** (string) - Required - Set to 'modal' for the overlay experience.
- **onComplete** (function) - Optional - Callback triggered upon successful payment.
- **onClose** (function) - Optional - Callback triggered when the user closes the modal.
```

--------------------------------

### xpay.initCheckout(options)

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Initializes a checkout session and returns an object containing session fields and action methods.

```APIDOC
## xpay.initCheckout(options)

### Description
Initialize a checkout session. Resolves with a merged object containing session fields and action methods.

### Parameters
- **options** (object) - Required - Configuration object including clientSecret, appearance, and locale.

### Example
```javascript
const checkout = await xpay.initCheckout({
  clientSecret: 'cs_test_abc_secret_xyz',
  appearance: { colorMode: 'dark' },
  locale: 'ar',
});
```
```

--------------------------------

### Initialize Checkout with elements

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Provides event-driven initialization for lower-level control over the checkout lifecycle.

```javascript
const xpay = await loadXPay('pk_test_xxx');
const elements = xpay.elements({ clientSecret });

elements.on('ready', ({ session }) => {
  console.log(session.status);         // { type: "open" }
  console.log(session.canConfirm);     // true
  console.log(session.amountTotal);    // 52450
  console.log(session.paymentMethods); // [{ type: 'card', ... }]
});

elements.on('loaderror', (event) => {
  // Only fires for actual failures (invalid secret, network error, etc.)
  // event: { type: "invalid_request_error" | "api_error" | "network_error", message, code?, param?, docUrl? }
  console.error('Failed to load:', event.message);
});

elements.on('error', (error) => {
  // Fires for unsolicited errors not triggered by a merchant action.
  // Examples: session expired during fee recalculation when switching payment methods, BIN detection failure.
  console.log(error.type);    // "invalid_request_error"
  console.log(error.code);    // "checkout_session_expired"
  console.log(error.message); // "This checkout session has expired"
  console.log(error.docUrl);  // "https://docs.xpay.app/api/errors#checkout_session_expired"
});
```

--------------------------------

### loadXPay(publishableKey)

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Loads the XPay SDK from the CDN. This should be called at the module level.

```APIDOC
## loadXPay(publishableKey)

### Description
Loads the XPay SDK from CDN. Returns a Promise. Call at module level, not inside components.

### Parameters
- **publishableKey** (string) - Required - The public key for your XPay account.

### Example
```javascript
import { loadXPay } from '@xpayeg/sdk';
const xpay = await loadXPay('pk_test_xxx');
```
```

--------------------------------

### xpay.elements(options)

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Creates an Elements instance for mounting payment elements.

```APIDOC
## xpay.elements(options)

### Description
Create an Elements instance for mounting payment elements.

### Parameters
- **options** (object) - Required - Configuration options for the elements instance.
```

--------------------------------

### xpay.checkout(options)

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Creates a drop-in checkout instance, either modal or inline.

```APIDOC
## xpay.checkout(options)

### Description
Create a drop-in checkout instance (modal or inline).

### Parameters
- **options** (object) - Required - Configuration options for the checkout instance.
```

--------------------------------

### initCheckout(options)

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Initializes a checkout session and returns an object containing session fields and action methods.

```APIDOC
## initCheckout(options)

### Description
Initializes a checkout session using a client secret. Returns a combined object containing session state fields and methods to interact with the checkout.

### Parameters
- **options** (object) - Required
  - **clientSecret** (string | Promise<string>) - Required - The client secret obtained from your server.

### Response
- **checkout** (object) - Returns an object containing:
  - **id** (string) - Session ID
  - **status** (SessionStatus) - Structured status object
  - **canConfirm** (boolean) - Whether the session is ready for confirmation
  - **amountTotal** (number) - Final total in smallest currency unit
  - **amountSubtotal** (number) - Subtotal before fees/discounts
  - **currency** (string) - ISO 4217 currency code
  - **merchantName** (string) - Merchant display name
  - **livemode** (boolean) - Whether live or test mode
  - **paymentMethods** (PaymentMethodInfo[]) - Available payment methods
  - **lineItems** (LineItemDto[]) - Line items with prices and quantities
  - **totalDetails** (TotalDetailsResponseDto) - Breakdown of fees, discounts, VAT
  - **discounts** (DiscountResponseDto[]) - Applied discounts
```

--------------------------------

### Implement Drop-in Modal Checkout

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Opens the full checkout experience in a modal overlay using the XPay SDK. Requires the SDK script to be loaded and a valid client secret.

```html
<button id="checkout-button">Pay Now</button>

<script src="https://checkout.xpay.app/v1/sdk.js"></script>
<script>
  document.getElementById('checkout-button').addEventListener('click', async () => {
    const xpay = XPay('pk_test_xxx');

    const checkout = xpay.checkout({
      clientSecret: 'cs_test_abc_secret_xyz',
      mode: 'modal',
      onComplete: (result) => {
        window.location.href = '/success';
      },
      onClose: () => {
        console.log('Customer closed checkout');
      },
    });

    checkout.open();
  });
</script>
```

--------------------------------

### elements(options)

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Initializes an event-driven interface for lower-level control over the checkout session.

```APIDOC
## elements(options)

### Description
Creates an elements instance for event-driven initialization. This allows listening to lifecycle events like 'ready', 'loaderror', and 'error'.

### Parameters
- **options** (object) - Required
  - **clientSecret** (string) - Required - The client secret obtained from your server.

### Events
- **ready** - Fired when the session is initialized. Provides the session object.
- **loaderror** - Fired on initialization failures (e.g., invalid secret, network error).
- **error** - Fired for unsolicited errors during the session lifecycle.
```

--------------------------------

### xpay.initCheckout

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Initializes the checkout session using a client secret.

```APIDOC
## xpay.initCheckout(options)

### Description
Initializes the checkout session to prepare for payment processing.

### Parameters
- **clientSecret** (string) - Required - The secret key provided by the server to initialize the session.
```

--------------------------------

### useCheckout()

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

React hook for managing checkout state and confirmation.

```APIDOC
## useCheckout()

### Description
A React hook provided by @xpayeg/react that manages loading states, error handling, and checkout confirmation.

### Returns
- **checkoutState** (object) - Contains the current state (loading, error, or checkout data).
- **confirm** (function) - A function to trigger the payment confirmation with customer details.
```

--------------------------------

### Initialize Checkout with initCheckout

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Initializes a checkout session and retrieves session fields and action methods in a single object.

```javascript
import { loadXPay } from '@xpayeg/sdk';

const xpay = await loadXPay('pk_test_xxx');

// Fetch client secret from your server
const { clientSecret } = await fetch('/api/create-checkout', { method: 'POST' }).then(r => r.json());

// Initialize checkout -- returns session data + action methods in one object
const checkout = await xpay.initCheckout({ clientSecret });

// Destructure session fields and actions together
const {
  status, currency, amountTotal, amountSubtotal, canConfirm, paymentMethods,
  confirm, applyPromotionCode, removePromotionCode, updateLineItemQuantity,
} = checkout;

// Display in your UI
document.getElementById('total').textContent =
  `${currency} ${(amountTotal / 100).toFixed(2)}`;
document.getElementById('methods').textContent =
  `Pay with: ${paymentMethods.map(pm => pm.displayName).join(', ')}`;
```

```javascript
const checkout = await xpay.initCheckout({
  clientSecret: fetch('/api/create-checkout', { method: 'POST' })
    .then(r => r.json())
    .then(data => data.clientSecret),
});
```

--------------------------------

### Integrate Checkout with React

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Uses the useCheckout hook from @xpayeg/react to manage loading, error, and checkout states. Requires the @xpayeg/react package.

```javascript
import { useCheckout } from '@xpayeg/react';

function CheckoutPage() {
  const checkoutState = useCheckout();

  if (checkoutState.type === 'loading') {
    return <Spinner />;
  }

  if (checkoutState.type === 'error') {
    return <div>Error: {checkoutState.error.message}</div>;
  }

  const { currency, lineItems, amountTotal, confirm } = checkoutState.checkout;

  return (
    <div>
      <h2>Total: {currency} {(amountTotal / 100).toFixed(2)}</h2>
      {lineItems?.map(item => (
        <div key={item.id}>{item.price.product.name} x {item.quantity}</div>
      ))}
      <button onClick={() => confirm({ customerDetails: { email } })}>Pay</button>
    </div>
  );
}
```

--------------------------------

### Import XPay TypeScript types

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Import the required types from the @xpayeg/sdk package to enable full TypeScript support.

```typescript
import type {
  XPayInstance, Elements, PaymentMethodInfo,
  CheckoutSession, SessionStatus, CustomerDetails, Appearance,
  InitCheckoutResult, CheckoutActions,
  ActionResult, XPayError,
  CheckoutLineItem, CheckoutTotalDetails, CheckoutFees, CheckoutDiscount,
} from '@xpayeg/sdk';
```

--------------------------------

### elements.create('payment')

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Creates a payment element to handle method selection and card input.

```APIDOC
## elements.create('payment')

### Description
Creates a payment element instance that can be mounted to the DOM.

### Methods
- **mount(selector)**: Mounts the payment element to the specified DOM element.
- **on('change', callback)**: Listens for changes in the payment form state.
```

--------------------------------

### Initialize Checkout Session

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Initialize a checkout session with a client secret and optional configuration.

```javascript
const checkout = await xpay.initCheckout({
  clientSecret: 'cs_test_abc_secret_xyz', // string | Promise<string>
  appearance: { colorMode: 'dark' },
  locale: 'ar',
});

// Session fields: status, canConfirm, amountTotal, currency, paymentMethods, lineItems, totalDetails, ...
// Action methods: confirm(), applyPromotionCode(), removePromotionCode(), updateLineItemQuantity(),
//                 submit(), fetchUpdates(), changeAppearance(), on(), getElements()
```

--------------------------------

### checkout.on('change', callback)

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Registers a listener for session changes, such as promo code updates, quantity changes, or payment method selection.

```APIDOC
## on('change', callback)

### Description
Registers a callback function that is triggered whenever the CheckoutSession is updated.

### Parameters
- **event** (string) - Required - Must be 'change'.
- **callback** (function) - Required - Function receiving the updated 'session' object.
```

--------------------------------

### Customize Checkout Appearance

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Override branding settings during initialization or update them dynamically using changeAppearance.

```javascript
const checkout = await xpay.initCheckout({
  clientSecret,
  appearance: {
    colorMode: 'dark',
    borderStyle: 'pill',
    inputStyle: 'filled',
    colors: { primary: '#FF6B35' },
  },
});

// Update later with changeAppearance()
checkout.changeAppearance({ colorMode: 'light' });
```

```javascript
const elements = xpay.elements({ clientSecret, appearance: { colorMode: 'dark' } });
elements.changeAppearance({ colorMode: 'light' });
```

--------------------------------

### Mount the Payment Element

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Initializes the checkout and mounts the payment element to a DOM node. The change event listener is used to toggle the submit button state based on form completion.

```javascript
const checkout = await xpay.initCheckout({ clientSecret });
const elements = checkout.getElements();

const paymentElement = elements.create('payment');
paymentElement.mount('#payment-element');

paymentElement.on('change', (event) => {
  submitButton.disabled = !event.complete;
  console.log(event.value.type);  // 'card', 'valu', etc.
});
```

--------------------------------

### checkout.applyPromotionCode

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Applies a promotion code to the current checkout session.

```APIDOC
## applyPromotionCode(code)

### Description
Applies a promotion code to the current checkout session.

### Parameters
- **code** (string) - Required - The promotion code string to apply.

### Returns
- **Promise** - Resolves to an object with type 'success' and the session, or type 'error' with an error message.
```

--------------------------------

### elements.fetchUpdates

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Forces a fresh fetch of the checkout session from the server.

```APIDOC
## fetchUpdates()

### Description
Forces a fresh session fetch from the server.

### Returns
- **Promise** - Resolves to an object with type 'success' and the updated session, or type 'error'.
```

--------------------------------

### xpay.confirmPayment(options)

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Confirms and submits a payment using the classic API.

```APIDOC
## xpay.confirmPayment(options)

### Description
Confirm and submit a payment (classic API).

### Parameters
- **options** (object) - Required - Configuration options for confirming the payment.
```

--------------------------------

### Retrieve Checkout Session on Server

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Fetches session details from the XPay API using a secret key to verify order status.

```javascript
// Your server -- retrieves session using your API key
app.get('/api/order-status', async (req, res) => {
  const response = await fetch(
    `https://api.xpay.app/checkout/sessions/${req.query.session_id}`,
    { headers: { 'Authorization': `Bearer ${process.env.XPAY_SECRET_KEY}` } },
  );
  const session = await response.json();
  res.json(session);
});
```

--------------------------------

### elements.submit

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Validates all fields in the payment form before confirmation.

```APIDOC
## elements.submit()

### Description
Validates all fields and returns the selected payment method if successful.
```

--------------------------------

### Handle Webhook Events

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Listens for checkout.session.completed events to trigger order fulfillment logic.

```javascript
app.post('/webhooks/xpay', (req, res) => {
  const event = req.body;

  if (event.type === 'checkout.session.completed') {
    fulfillOrder(event.data);  // Ship product, send email, update DB
  }

  res.json({ received: true });
});
```

--------------------------------

### Check Session Status

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Demonstrates how to handle the structured status object returned by the checkout session.

```javascript
// Check session status
if (checkout.status.type === 'open') {
  // Session is active, show payment form
}

if (checkout.status.type === 'expired') {
  // Session expired, show message or create a new one
  showMessage('This checkout session has expired.');
}

if (checkout.status.type === 'complete') {
  // Payment finished -- check paymentStatus for details
  console.log(checkout.status.paymentStatus); // "paid"
  showMessage('Payment successful!');
}
```

--------------------------------

### Display Order Status on Client

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Retrieves the session ID from the URL and updates the DOM with payment status and order totals.

```javascript
const sessionId = new URLSearchParams(window.location.search).get('session_id');
const session = await fetch(`/api/order-status?session_id=${sessionId}`).then(r => r.json());

document.getElementById('status').textContent =
  session.paymentStatus === 'paid' ? 'Payment Confirmed' : 'Processing...';
document.getElementById('total').textContent =
  `${session.currency} ${(session.amountTotal / 100).toFixed(2)}`;

// Amounts breakdown
// session.totalDetails.amountDiscount       -- 0
// session.totalDetails.amountPlatformFee    -- 1750 (Processing Fee, if fees pass-through)
// session.totalDetails.amountCollectedVat   -- 700  (VAT)
// session.totalDetails.amountShipping       -- 0
// session.totalDetails.amountTax            -- 0

// Line items
session.lineItems?.forEach(item => {
  console.log(item.price.product.name, 'x', item.quantity, '=', item.amountTotal);
});
```

--------------------------------

### Listen for Session Changes

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Event listeners to react to session updates, including amount breakdowns and item changes.

```javascript
// initCheckout -- use on('change', ...)
checkout.on('change', (session) => {
  totalDiv.textContent = `Total: ${session.currency} ${(session.amountTotal / 100).toFixed(2)}`;

  // Amounts breakdown via totalDetails
  console.log(session.totalDetails?.amountPlatformFee);   // Processing fee
  console.log(session.totalDetails?.amountCollectedVat);   // VAT
  console.log(session.totalDetails?.amountDiscount);       // Discount amount
  console.log(session.totalDetails?.amountShipping);       // Shipping
  console.log(session.totalDetails?.amountTax);            // Tax

  console.log(session.discounts);   // Applied discounts
  console.log(session.lineItems);   // Updated line items
});
```

```javascript
elements.on('change', (session) => {
  console.log(session.amountTotal);
  console.log(session.totalDetails?.amountPlatformFee);
});
```

--------------------------------

### Pre-validation with submit()

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Validates form fields before proceeding to confirm the payment.

```javascript
const { error, selectedPaymentMethod } = await elements.submit();
if (error) {
  errorDiv.textContent = error.message;
  return;
}

// Fields are valid, proceed to confirm
const result = await checkout.confirm({ paymentMethod: selectedPaymentMethod });
```

--------------------------------

### Refresh Session Data

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Manually trigger a fetch to synchronize the local session state with the server.

```javascript
const result = await elements.fetchUpdates();
if (result.type === 'success') {
  console.log('Session refreshed:', result.session.amountTotal);
}
```

--------------------------------

### checkout.confirm

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Confirms the payment and handles the transaction outcome.

```APIDOC
## checkout.confirm(options)

### Description
Confirms the payment transaction. Returns a tagged union result.

### Parameters
- **customerDetails** (object) - Optional - Object containing email, name, and phone.
- **redirect** (string) - Optional - Defines redirect behavior: 'always' or 'if_required' (default).
```

--------------------------------

### Migrate from CardElement to PaymentElement

Source: https://github.com/xpayeg/xpay-js/blob/main/CHANGELOG.md

Replace the deprecated card element with the unified payment element to support all payment methods.

```ts
// Before
const cardElement = elements.create("card");
cardElement.mount("#card");

// After
const paymentElement = elements.create("payment");
paymentElement.mount("#payment");
```

--------------------------------

### Confirm Payment

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Confirms the payment session. The redirect behavior can be controlled via the redirect parameter.

```javascript
// Default behavior: returns result to your code (no redirect)
const result = await checkout.confirm({
  customerDetails: {
    email: 'customer@example.com',
    name: 'Ahmed Hassan',
    phone: '+201234567890',
  },
});

if (result.type === 'error') {
  errorDiv.textContent = result.error.message;
} else {
  console.log(result.session.status); // { type: "complete", paymentStatus: "paid" }
  window.location.href = '/thank-you';
}
```

```javascript
await checkout.confirm({
  customerDetails: {
    email: 'customer@example.com',
    name: 'Ahmed Hassan',
  },
  redirect: 'always', // Redirect to afterCompletion.redirect.url
});
// ^ If successful, the page navigates away. Code below only runs on error.
```

--------------------------------

### Update Checkout Session State

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Methods to apply or remove promotion codes and update line item quantities within the checkout session.

```javascript
// Apply promotion code
const result = await checkout.applyPromotionCode('SAVE20');
if (result.type === 'error') {
  errorDiv.textContent = result.error.message; // e.g., "Invalid promotion code"
} else {
  console.log('New total:', result.session.amountTotal);
}

// Remove promotion code
await checkout.removePromotionCode();

// Update line item quantity (object param, not positional)
await checkout.updateLineItemQuantity({ lineItem: 'li_abc123', quantity: 3 });
```

--------------------------------

### checkout.updateLineItemQuantity

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Updates the quantity of a specific line item in the checkout session.

```APIDOC
## updateLineItemQuantity(params)

### Description
Updates the quantity of a specific line item.

### Parameters
- **params** (object) - Required - Object containing 'lineItem' (string) and 'quantity' (number).
```

--------------------------------

### checkout.removePromotionCode

Source: https://github.com/xpayeg/xpay-js/blob/main/README.md

Removes the currently applied promotion code from the checkout session.

```APIDOC
## removePromotionCode()

### Description
Removes the currently applied promotion code from the checkout session.
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.