JavaScript日期比较无法正确评估

Question

此表达式的评估结果为true。为什么呢？

if ($scope.state.dateStart < $scope.state.previousStart || $scope.state.dateEnd > $scope.state.previousEnd) {

调试时，我可以看到值是相同的，因此表达式不应该为真：

编辑：在某些时候，之前的值设置如下：

$scope.state.previousStart = new Date($scope.state.dateStart);
$scope.state.previousEnd = new Date($scope.state.dateEnd);

编辑：这是角度工厂，显示最初如何定义值。

app.factory('historyRepository', ['$http', '$rootScope', function ($http, $rootScope) {
    var state = {
        allBatches: [],
        filteredBatches: [],
        selectedBatch: null,
        allStatuses: [],
        dateStart: new Date(),
        dateEnd: new Date(),
        previousStart: new Date(),
        previousEnd: new Date()
    }

    // Set initial start and end date times
    var date = new Date();
    date.setDate(date.getDate() - 7); // 7 days ago
    state.dateStart = new Date(date);
    state.previousStart = new Date(date);
    state.dateEnd.setHours(23, 59, 59, 999); // Use ending of end date. (hour,min,sec,millisec)
    state.previousEnd.setHours(23, 59, 59, 999); // Use ending of end date. (hour,min,sec,millisec)

    return state;
}]);

Answer 1

问题在于我的结束日期;具体而言，毫秒。使用现有日期设置日期时，不设置毫秒。需要设置毫秒才能使日期相等。

$scope.state.previousEnd = new Date($scope.state.dateEnd);
$scope.state.previousEnd.setMilliseconds(999);
// Now previousEnd and dateEnd are the same.

通过这样做，我能够看到日期不一样：

// Show milliseconds since January 1, 1970
console.log('dateEnd', $scope.state.dateEnd.getTime());
console.log('previousEnd', $scope.state.previousEnd.getTime());

这是输出：

    dateEnd 1476331199999
previousEnd 1476331199000