Implement your own Back In Stock with this Javascript script:
pushowl.registerForEvent('back_in_stock', enableHintScreen)
The above function returns a promise with the following success and return
Success:
Return an object in the form of:
{'pushowl_subscriber_token': <PUSHOWL SUBSCRIPTION TOKEN>}
pushowl_subscriber_token: It's a string in the form of a guid which is used to identify the subscriber in pushowl
Error:
Returns an error code:
{'error_code': <ERROR CODE>}
permission_not_granted : If the user denies permission to push notification.
unknown_event: If an incorrect value is passed to registerForEvent function