function isNodeAfter (sourceNode, targetNode) {

	return !!(
		sourceNode &&
		targetNode &&
		sourceNode.compareDocumentPosition(targetNode) & 2 // 2 : Node.DOCUMENT_POSITION_PRECEDING
	);
}
Returns true if targetNode appears after sourceNode in the dom.
@param {HTMLElement} sourceNode - the source node for comparison
@param {HTMLElement} targetNode - the node to compare against sourceNode