AngularJS element.innerHTML未在指令中定义

Let's say I have:

假设我有：

directives.directive('foo', function () {
    return {
        restrict:'A',
        scope: true,
        link:function (scope, element, attr) {

            console.log('innerHTML is ' + element.innerHTML);

            scope.$watch('update', function (newValue) {
                console.log('innerHTML is... ' + element.innerHTML);
            });

        }
    }
});
directives.directiv