When registering an event via addEventListener on an element, then delete that element without removing the event, and doing so repeatedly, would memory be \"leaked\"?
You will get memory leak if you delete from DOM, elements that have attached listeners. But this only occurs in IE, Fx and others have advanced GC.
Often it happens, if you manipulate with DOM elements not via DOM, but like
el.innerHTML = ...
For example, YUI has custom realization setInnerHTML, to prevent memory leak in this case.