//回到顶部app.directive('scrollTop', function ($window, $document, $compile) {    return {        restrict: 'A',        link: function ($scope, elem, attr, ctrl) {            var elShare = angular.element('');            function showShare() {                if (!elShare.hasClass('ng-scope')) {                    $compile(elShare)($scope);                    var body = $document.find('body').eq(0);                    body.append(elShare);                }                elShare.show();            }            var loading = false;            $scope.goTop = function () {                var idToScroll = attr.href;                var $target;                if (idToScroll) {                    $target = $(idToScroll);                } else {                    $target = elem;                }                loading = true;                $("body").animate({ scrollTop: $target.offset().top }, "fast", function () {                    elShare.hide();                    loading = false;                });            }            //http://stackoverflow.com/questions/13549216/changing-css-on-scrolling-angular-style            var scrollTop = 0;            var windowEl = angular.element($window);            var handler = function () {                if (loading) return;                var ele = document.body;                if (ele.scrollTop > 50 && scrollTop < ele.scrollTop) {                    showShare();                }                else {                    elShare.hide();                }                scrollTop = document.body.scrollTop;            }            windowEl.on('scroll', $scope.$apply.bind($scope, handler));            handler();        }    };});