Callback to execute additional logic before opening the Payment Request UI

[socsieng]

Discussed in #91

^{Originally posted by nielsengoncalves July 7, 2021}
Hello,

We're using the React component and we have a requirement that we need to do some additional logic when user clicks the Google Pay button before opening the popup.

It would be nice if there was a possibility to use some of components callback to achieve that, something such as onSelect or any other naming that fits better.

<GooglePayButton
  environment="TEST"
  paymentRequest={{...}}
  onSelect={() => {
    // Additional logic that should happen before popup is open
  }}
/>