One of the things with using event listeners in JavaScript is that it causes memory leaks. This causes the website performance to slow down after a while. A pretty good description of how and why these memory leaks happen is explained here.
In Dojo, attaching events to an element are done as below:
dojo.connect(dojo.byId('elementId'), 'onclick'/*or other events*/, scope/*context*/, function(event) {
//do something when the event happens.
});
Eugene Lazutkin’s solution here on StackOverflow is perfect in my opinion. I’ve started using it in all the Dijit widgets I’ve been writing. I put this in the destroy() method of the widget.
dojo.forEach(handles, dojo.disconnect);
JavaScript rambles 
The most unsafe practice that would create a memory leak is to do
document.getElementById(“x”).innerHTML=””;
you would avoid memory leaks only if you remove all event listeners on all element inside the element to be removed . Does your code take care of just that element or all the elements inside this element!
I am not sure, the dojo.disconnect removes event handlers to the element you initially appended to, if the reference to the element is no longer available as a result of using innerHTML, then I dont think it would help. I guess the right way is to stick to using innerHTML to set text content only, and not for any other dom manipulation.