[bits in extension]how can i figure which event should be fired when transactionCompleted?

i have set big fireworks event and small fireworks event with the same sku.
when i listened window.Twitch.ext.bits.onTransactionComplete(), how can i figure which fireworks should be fired?
the transaction cant help me to figure what should i do when all the product with one sku.

If you use the same SKU for multiple products then you’d need to store what product the user selected on their side.

For example, when a use selects Big Fireworks, store that selection in a variable, and then when onTransactionComplete fires, check what is stored in that variable. If you then need to send that to your EBS you can do so but as it’s not in the receipt there’ll be nothing that prevents the user sending a different value. For example they could have selected Small Fireworks, gone through the transaction, but actually send Big Fireworks to your EBS and there’s no way for you to know it was changed as it’s not part of the receipt.

As noted already there is not additional data so you have to track it yourself.

But there is this uservoice requesting something along these lines