event_delegation.js

/*
DOM event delegation is a mechanism of responding to ui-events via a single common parent rather 
than each child, through the magic of event "bubbling" (aka event propagation).
When an event is triggered on an element, the following occurs:

The event is dispatched to its target  EventTarget and any event listeners found there are triggered. 
Bubbling events will then trigger any additional event listeners found by following 
the EventTarget's parent chain upward, checking for any event listeners registered 
on each successive EventTarget. This upward propagation will continue up to and including the Document.
*/