Give arguments to the polling

[cGuille]

It would be nice to be able to provide arguments to the polling function. For instance, we could write a polling to retrieve the private messages of a user on a website:

// Define a polling that fetch a user's messages by GETting a resource
var polling = AsyncPolling(function(userId, end) {
    var userMessagesUrl = 'http://example.com/messages/user/' + encodeURIComponent(userId);
    fetch(userMessagesUrl).then(function (response) {
        var messages = // extract messages from response
        end(null, messages);
    }).catch(end);
}, 2000);

// Attach a listener to display the messages when they are received:
polling.on('result', function (messages) {
    // Do something with the messages
});

// Run the polling for a user with ID `1`:
polling.run(1);

// Let's say they disconnect and another user log in:
polling.stop()
polling.run(newUserId);

I find this cleaner than relying on a global state or something like that.