[PHP] Sending Email Notification in Facebook JavaScript API

Question

I'm trying to send a email notification to the user from my Facebook application. I'm trying to use the FaceBook JavaScript API function

notifications_sendEmail(Array recipients,  String subject,  String text,  String fbml,  Object onRequestCompleted)

I can understand the first four parameters. But what's the usage of the last parameter 'onRequestCompleted'. The Doc says it's the call back function. But, what if I do not want to execute a call back function? In this case, what will be a valid values to the parameter onRequestCompleted?

Answer 1

null or, for this function, just leave it blank. Some functions in the Facebook JS client library seem to require values, even if they're just explicitly nulled, so it might be best to get into the habit of passing as many parameters as a function needs and nulling the ones that you aren't making use of.