count angular watchers

watchersCount.js

(function () { 
    var root = angular.element(document.getElementsByTagName('body'));
    var watchers = [];

    var f = function (element) {
        if (element.data().hasOwnProperty('$scope')) {
            angular.forEach(element.data().$scope.$$watchers, function (watcher) {
                watchers.push(watcher);
            });
        }

        angular.forEach(element.children(), function (childElement) {
            f(angular.element(childElement));
        });
    };

    f(root);

    console.log(watchers.length);
})();

// http://stackoverflow.com/a/18526757/967859