if (mutationObserver) mutationObserver.disconnect()
var mutationObserver = new MutationObserver(function(mutations) {
	mutations.forEach(function(mutation) {
 		if (mutation.addedNodes.length === 0 && mutation.removedNodes.length === 0 && mutation.attributeName === "class") {
			mutation.target.dispatchEvent(new CustomEvent('classChanged', {bubbles: true, detail: {}}))
 		}
	})
})
mutationObserver.observe(document.documentElement, {attributes: true, subtree: true})
function callback() {
	console.log(this, arguments)
}
var candidates = document.querySelectorAll('.candidate')
for(var i = 0; i < candidates.length; i++) {
	candidates[i].addEventListener('classChanged', callback, false)
}