[JS] mutationObserver for class

var target = document.querySelector('.search-box');
​
// create an observer instance
var observer = new MutationObserver(function (mutations) {
    console.log(mutations);
    $('#search-dropdown').val('');
​
});
​
// configuration of the observer:
var config = {
    attributes: true,
    childList: true,
    characterData: true,
    attributes: true,
    attributeOldValue: true,
    attributeFilter: ['class']
};
​
// pass in the target node, as well as the observer options
observer.observe(target, config);