JavaScript return value: What does <> mean?

Question

I am trying to use the API in this page.

The definition is like this below:

vline.Promise.<vline.Collection> getMessages([Number opt_limit])

I want to use the return value of this API, however I don't understand what the <> means. I have researched about the JavaScript language but I couldn't find any clues.

My script is:

vlinesession.getPerson(userId).done(function(person) {       
    person.postMessage(msg); //it works.
    var log = person.getMessages(20); //how can I parse 'log'?
}

Can anyone give me a hint or some samples on how to use this API?

Answer 1

@cbuckley is correct in his description, but I want to expand on it and give an example.

vline.Promise.<vline.Collection> getMessages([Number opt_limit])

This indicates that it is returning a vline.Promise with the result to the success callback being of type vline.Collection.

Here's an example:

vlinesession.getPerson(userId).done(function(person) {       
    person.getMessages().done(function(msgCollection) {   // msgCollection is a vline.Collection of vline.Message's
        for (var i = 0; i < msgCollection.getSize(); i++) {
            var msg = msgCollection.getAt(i);       // this is the vline.Message
            console.log('Message from: ' + msg.getSender() + 
                        ' with body: ' + msg.getBody());
        }
    }); 
});

Note that I left out the fail handlers for brevity, but you should include those as well to make your code robust.

Answer 2

This is explained on the vline.Promise documentation page:

In the documentation, you will frequently see functions with a return value of the form vline.Promise.<foo.Bar>. This is a short-hand way of saying that the function returns a Promise and the result provided to success callbacks on that Promise will be of type foo.Bar. We may refer to this less formally as a "promise of a foo.Bar".

Answer 3

<vline.Collection> should be replaced with something else, it's not javascript syntax.