use-nsISimpleEnuerator.js

// Ci is a shorthand for Components.interfaces that has to be defined beforehand.
var enumerator; // is a nsISimpleEnumberator

// Adjust the elementInterface to support your needs / what the enumerator actually provides. Feel free to hard code that instead of doing it this way.
var element, elementInterface = "nsISupports";
while(enumerator.hasMoreElements()) {
    element = enumerator.getNext().QueryInterface(Ci[elementInterface]);
    // do stuff with element
}