Have a look at this page's source code to see the additions to the DOM for working with pseudo-elements.
        window.getPseudoElements(element, type) can be used to get a list of an element's pseudo-elements where:
    
element is a reference to the host DOM elementtype is either "before" or "after" and represents the type of the pseudo-elementsThe demo works correctly if both the 'control' and 'pseudo-elements' sections look exactly the same. Take a look at the source code.