> ## Documentation Index
> Fetch the complete documentation index at: https://docs.upstackdata.com/llms.txt
> Use this file to discover all available pages before exploring further.

# transactionId / orderId

> Unique identifier for the order. Use either transactionId or orderId.

Unique identifier for the order. Use either `transactionId` or `orderId` — they're interchangeable.

```javascript theme={null}
window._upstack('track', 'purchase', {
  transactionId: 'ORD-2026-001',  // or orderId: 'ORD-2026-001'
  value: 149.99,
  currency: 'USD'
});
```

| Type   | Required                | Events           |
| ------ | ----------------------- | ---------------- |
| string | Yes for purchase/refund | purchase, refund |

<Note>
  For Shopify stores, this is typically the Shopify order ID (e.g., `shopify_order_5678901234`).
</Note>

## Related Properties

<CardGroup cols={2}>
  <Card title="orderName" icon="hashtag" href="/pixel/events/properties/order-name">
    Human-readable order number shown to customers.
  </Card>

  <Card title="value" icon="coins" href="/pixel/events/properties/value">
    The monetary value of the order.
  </Card>
</CardGroup>