How can I tell if an object is a jQuery Promise/Deferred?

Question

I have a function that takes a single argument. I need to be able to tell if this argument is a jQuery Promise or Deferred object. If not, then the val

Answer 1

The quick-and-dirty solution is to test if the object has a then function:

if (typeof message.then === 'function') {
    //assume it's a Deferred or fits the Deferred interface
} else {
    //do other stuff
}