documentcloud/backbone — pull request #1465 by avanderhoorn (2012-06-28 05:56:23+00:00)
Title: Backbone.Events.onMany - Only trigger callback once all child events have triggered at least once.

This feature allows for multiple events to be registered along with a single callback. The callback only is triggered once all the events have been executed at least once. This is useful when needing to wait for multiple events to occur before you want to execute the callback.

I'm not sure if this is a feature you want in core, but its been very useful for me as my work is usually based on a composition of multiple events.

I don't have any tests for this, but I wanted to get your feedback before spending more time with this. Let me know what you think.

Cheers
Anthony