AngularJS Countdown Directive

example.html

<time ng-countdown="1411225200" ng-countdown-finished="toggle()">
    <ul class="timer_wrap">
        <li class="days">
            <span class="value" ng-bind="days">-</span>
            <span class="label">days</span>
        </li>
        <li class="hours">
            <span class="value" ng-bind="hours">--</span>
            <span class="label">hours</span>
        </li>
        <li class="minutes">
            <span class="value" ng-bind="minutes">--</span>
            <span class="label">minutes</span>
        </li>
        <li class="seconds">
            <span class="value" ng-bind="seconds">--</span>
            <span class="label">seconds</span>
        </li>
    </ul>
</time>

ng-countdown.js

app.directive('ngCountdown', function() {
    return {
        restrict: 'A',
        controller: function($scope, $attrs, $timeout) {
            var ds = new Date();
            ds.setTime($attrs.ngCountdown * 1000);

            $scope.days = '-';
            $scope.hours = $scope.minutes = $scope.seconds = '--';

            $scope.timeout = $timeout(update, 1000);

            function update() {
                now = +new Date();

                $scope.delta = Math.round((ds - now) / 1000);
                if ($scope.delta >= 0) {
                    $timeout(update, 1000);
                } else if ($attrs.ngCountdownFinished) {
                    $scope.$apply($attrs.ngCountdownFinished);
                }
            }

        },
        link: function($scope, $element, $attrs) {
            $scope.$watch('delta', function(delta) {
                if (typeof delta === 'undefined') return;

                if (delta < 0) {
                    delta = 0;
                }

                $scope.days = Math.floor(delta / 86400);
                $scope.hours = forceTwoDigits(Math.floor(delta / 3600) % 24);
                $scope.minutes = forceTwoDigits(Math.floor(delta / 60) % 60);
                $scope.seconds = forceTwoDigits(delta % 60);
            });

            function forceTwoDigits(num) {
                return String(num < 10 ? '0' + num : num);
            }

        }
    }
});