observer.disconnect();
// select the target node
var target = document.querySelector('#chat'),
searchString = 'hello';
// create an observer instance
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(mutation) {
var addedNodes = mutation.addedNodes;
for (var i = 0; i < addedNodes.length; i++){
if (mutation.addedNodes[i].classList &&
mutation.addedNodes[i].classList.contains('message') &&
! mutation.addedNodes[i].classList.contains('pending')/* &&