Compare dates with momentjs in angularjs

The problem is this:

// Creas un String con la fecha
$scope.a="26-04-2016"; 

$scope.c = 
    // Creas un objeto moment a partir de ese String
    moment($scope.a,"DD-MM-YYYY")

    // Vuelves a convertir dicho objeto moment a String
    // que es exactamente igual a $scope.a
    .format("DD-MM-YYYY");

    // String --> moment --> String

This is redundant and it is also the reason that you are comparing dates as strings, not as Datejavascript objects and when you compare strings they will give you more or less according to a comparison algorithm that follows different steps (step 4) as if both operands of the algorithm were dates (step 3).

var $scope = {};

$scope.a = "26-04-2016";
$scope.b = "20-10-2016";

$scope.a1 = new Date('2016-04-26');
$scope.b1 = new Date('2016-10-20');

//$scope.a >= $scope.b => true
console.log('$scope.a >= $scope.b :', $scope.a >= $scope.b);
// "26" >= "20" => true
console.log('"26" >= "20" :', "26" >= "20");
//$scope.a1 >= $scope.b1 => false
console.log('$scope.a1 >= $scope.b1 :', $scope.a1 >= $scope.b1);

So the possible solutions can be

1. Don't dispose of the momentoriginal object and use it to do the comparisons using the methods (recommended)

   isSame( ===)

   isBefore( <)

   isAfter( >)

   isSameOrBefore( <=)

   isSameOrAfter( >=)

   Here is an example

angular.module('app', [])
  .controller('DateCtrl', function($scope) {

    $scope.a = "26-04-2016";
    $scope.c = moment($scope.a, "DD-MM-YYYY");
    $scope.b = "20-10-2016";
    $scope.d = moment($scope.b, "DD-MM-YYYY");

    if ($scope.d.isSameOrBefore($scope.c)) {
      alert($scope.b + ' es menor a ' + $scope.a)
    } else {
      alert($scope.b + ' es mayor a ' + $scope.a)
    }

  });

<script src="http://momentjs.com/downloads/moment.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="app" ng-controller="DateCtrl">
  {{a}}
  <br>{{b}}
</div>

2. Convert the momentto Dateand compare using the corresponding methods

angular.module('app', [])
  .controller('DateCtrl', function($scope) {
    // Tambien puedes descomponer las fechas y crear el objeto Date directamente
    $scope.a = "26-04-2016";
    $scope.c = moment($scope.a, "DD-MM-YYYY").toDate();
    $scope.b = "20-10-2016";
    $scope.d = moment($scope.b, "DD-MM-YYYY").toDate();

    if ($scope.d <= $scope.c) {
      alert($scope.b + ' es menor a ' + $scope.a)
    } else {
      alert($scope.b + ' es mayor a ' + $scope.a)
    }

  });

<script src="http://momentjs.com/downloads/moment.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="app" ng-controller="DateCtrl">
  {{a}}
  <br>{{b}}
</div>

Finally I recommend that you manipulate your dates using the ISO 8601 format . This is not mandatory but it is the standard and it will save you from having to do a lot of date format conversions in your programs.

You can also compare them as JSON, i.e.:

if($scope.d.toJSON() <= $scope.d.toJSON())

Just yesterday I tried it with AngularJS (Angular 1) and it worked :)

.format() converts the date (the moment object) to a text string. If you use the standard format, sorting by year, month, day would not be a problem. But you are indicating that the output format is day, month, year, so when comparing the text strings it will treat them as numbers, not as dates, so 26042016 is greater than 20102016.

The solution is to compare the moment objects directly, or with the moment comparison functions: isBefore() and isAfter(). Then the format is given at the time of displaying the variable.

$scope.a="26-04-2016";    
$scope.c = moment($scope.a,"DD-MM-YYYY");
$scope.b="20-10-2016";
$scope.d = moment($scope.b,"DD-MM-YYYY");
if($scope.d <= $scope.c){
    alert($scope.d.format("YYYY-MM-DD") + ' es menor a  '+ $scope.c.format("YYYY-MM-DD"))
}else{
    alert($scope.d.format("YYYY-MM-DD") + ' es mayor a ' + $scope.c.format("YYYY-MM-DD"))
}

I can't test it but I think this will work for you

$scope.a="26-04-2016";    
$scope.c = moment($scope.a,"DD-MM-YYYY").format("YYYY-MM-DD");
$scope.b="20-10-2016";
$scope.d = moment($scope.b,"DD-MM-YYYY").format("YYYY-MM-DD");
if($scope.d <= $scope.c){
    alert($scope.d+' es menor a '+$scope.c)
}else{
    alert($scope.d+' es mayor a '+$scope.c)
}