Full Integration Example

Two ready-to-run snippets: pick the one that matches your backend.

Basic: the order ID (invoiceId) is known at page-load time. Pass it to init() and you are done.
CMS pattern: the order does not exist yet at page-load (typical for WooCommerce, Magento, OpenCart, custom platforms). When the customer taps the WeChat Pay button, your backend creates the order and returns the resulting invoiceId (and a fresh access token, if needed) through onBeforeProcessPayment.

Both snippets pass paymentData (with amount + currency) and token to init(). The component opens a QR modal with a built-in countdown (default 15 minutes).

Dynamic carts

If the cart amount can change after the button is rendered (quantity edits, coupons), you have two options:

Fetch values on every click. Skip paymentData and token at init() entirely; return fresh values from onBeforeProcessPayment based on the current cart state. This is the simplest path for highly dynamic carts, no re-init needed.
Re-initialize on change. If you do pass paymentData and token at init(), call init() again with fresh values whenever the cart changes. The access token is minted for the values you passed and the backend rejects mismatches.

Basic
CMS pattern

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <script src='https://test-pay.dnapayments.com/components/alipay-wechat-pay/alipay-wechat-pay-component.js'></script>
    <script>
        async function renderWeChatPay() {
            const token = 'YOUR_ACCESS_TOKEN';

            const paymentData = {
                amount: 24,
                currency: 'GBP',
                invoiceId: 'YOUR_INVOICE_ID',
                description: 'Shoes',
                paymentSettings: {
                    terminalId: 'YOUR_TERMINAL_ID',
                    callbackUrl: 'https://example.com/callback',
                    failureCallbackUrl: 'https://example.com/failure-callback'
                },
                customerDetails: {
                    accountDetails: { accountId: 'uuid000001' },
                    billingAddress: {
                        firstName: 'John', lastName: 'Doe',
                        addressLine1: 'Fulham Rd',
                        postalCode: 'SW6 1HS', city: 'London', country: 'GB'
                    },
                    email: 'example@email.com',
                    mobilePhone: '+441234567890'
                },
                orderLines: [{
                    name: 'Running shoe',
                    quantity: 1,
                    unitPrice: 24,
                    taxRate: 20,
                    totalAmount: 24,
                    totalTaxAmount: 4,
                    imageUrl: 'https://www.example.com/logo.png',
                    productUrl: 'https://www.example.com/AD6654412.html'
                }]
            };

            const events = {
                onClick: () => {
                    console.log('WeChat Pay button clicked');
                },
                onError: (error) => {
                    console.error('WeChat Pay error:', error);
                },
                onCancel: () => {
                    console.log('Payment cancelled');
                },
                onPaymentSuccess: (result) => {
                    console.log('Payment processed', result);
                    window.location.href = '/success';
                }
            };

            window.DNAPayments.WeChatPayComponent.init({
                containerElement: document.getElementById('wechat-pay-btn-container'),
                paymentData,
                events,
                token,
                paymentTimeoutInSeconds: 900   // optional, default
            });
        }

        window.addEventListener('load', renderWeChatPay);
    </script>
</head>
<body>
    <div id='wechat-pay-btn-container' style='width: 100%; height: 46px;'></div>
</body>
</html>

Use this shape when the order is created server-side at the moment the customer commits to pay. After the customer taps the WeChat Pay button, onBeforeProcessPayment calls your backend to create the order, gets a freshly minted access token bound to the new invoiceId, and returns both to the component. The component then opens the QR modal using these refreshed values.

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <script src='https://test-pay.dnapayments.com/components/alipay-wechat-pay/alipay-wechat-pay-component.js'></script>
    <script>
        async function renderWeChatPay() {
            // paymentData passed at init() does NOT contain invoiceId yet.
            // amount and currency are required so the access token can be bound
            // to the correct total.
            const paymentData = {
                amount: 24,
                currency: 'GBP',
                description: 'Shoes',
                paymentSettings: {
                    terminalId: 'YOUR_TERMINAL_ID',
                    callbackUrl: 'https://example.com/callback',
                    failureCallbackUrl: 'https://example.com/failure-callback'
                },
                customerDetails: {
                    accountDetails: { accountId: 'uuid000001' },
                    billingAddress: { country: 'GB' }
                },
                orderLines: [{
                    name: 'Running shoe',
                    quantity: 1,
                    unitPrice: 24,
                    taxRate: 20,
                    totalAmount: 24,
                    totalTaxAmount: 4
                }]
            };

            const events = {
                onClick: () => {
                    console.log('WeChat Pay button clicked');
                },
                // Fires after the click and before the QR is requested.
                // The server creates the order and issues a token bound to it,
                // then returns the refreshed paymentData and token. The locked
                // fields (amount, currency, delivery address) must match init().
                onBeforeProcessPayment: async () => {
                    const { invoiceId, token } = await fetch('/api/create-order-and-token', {
                        method: 'POST',
                        headers: { 'Content-Type': 'application/json' },
                        body: JSON.stringify({ amount: paymentData.amount, currency: paymentData.currency })
                    }).then(r => r.json());

                    return {
                        paymentData: { ...paymentData, invoiceId },
                        token
                    };
                },
                onPaymentSuccess: (result) => {
                    console.log('Payment processed', result);
                    window.location.href = '/success';
                },
                onCancel: () => {
                    console.log('Payment cancelled');
                },
                onError: (error) => {
                    console.error('WeChat Pay error:', error);
                }
            };

            window.DNAPayments.WeChatPayComponent.init({
                containerElement: document.getElementById('wechat-pay-btn-container'),
                paymentData,
                events,
                token: 'BOOTSTRAP_ACCESS_TOKEN'  // replaced by the one returned from onBeforeProcessPayment
            });
        }

        window.addEventListener('load', renderWeChatPay);
    </script>
</head>
<body>
    <div id='wechat-pay-btn-container' style='width: 100%; height: 46px;'></div>
</body>
</html>

Switch to production

Replace the script source with the production CDN before going live:

<script src='https://pay.dnapayments.com/components/alipay-wechat-pay/alipay-wechat-pay-component.js'></script>

See Deployment for the full go-live checklist.