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AngularJS angular.isUndefined() Function

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  • Last Updated : 08 Nov, 2022
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The angular.isUndefined() function in AngularJS is used to determine the value inside isUndefined function is undefined or not. It returns true if the reference is undefined otherwise returns false. 

Syntax:

angular.isUndefined( value )

Parameter value:

  • value: It is used to reference the value to check whether the value is defined or undefined.

Return Value: It returns true if the value passed is undefined else returns false. 

Example 1: This example uses angular.isUndefined() function in AngularJS to determine the value inside the isUndefined function is undefined or not. 

HTML




<!DOCTYPE html>
<html>
  
<head>
    <title>angular.isUndefined() function</title>
    <script src=
"//ajax.googleapis.com/ajax/libs/angularjs/1.3.2/angular.min.js">
    </script>
</head>
  
<body ng-app="app" style="text-align:center">
    <h1 style="color:green">GeeksforGeeks</h1>
    <h2>angular.isUndefined()</h2>
  
    <div ng-controller="isDefinedController">
        <b>Date:</b> {{date}}<br><br>
        {{isUndefined}}
        <br><br><br>
        <b>Date1:</b> {{date1}}<br><br>
        {{isUndefined1}}
    </div>
  
    <script>
        var app = angular.module("app", []);
        app.controller('isDefinedController',
            ['$scope', function ($scope) {
                $scope.date = new Date;
                $scope.date1;
  
                $scope.isUndefined = angular.isUndefined($scope.date)
                    == true ? "$scope.date is Undefined."
                    : "$scope.date is not Undefined.";
  
                $scope.isUndefined1 = angular.isUndefined($scope.date1)
                    == true ? "$scope.date1 is Undefined."
                    : "$scope.date1 is not Undefined.";
            }]);
    </script>
</body>
  
</html>


Output:

 

Example 2:  This example uses angular.isUndefined() function in AngularJS by verifying the defined & undefined values.

HTML




<!DOCTYPE html>
<html>
  
<head>
      <title>angular.isUndefined() function</title>
    <script src=
    </script>
    <style>
        body {
            text-align: center;
            font-family: 'Times New Roman', Times, serif;
        }
  
        h1 {
            color: green;
        }
    </style>
</head>
  
<body ng-app="App">
    <h1>GeeksforGeeks</h1>
    <h3>angular.isUndefined() Function</h3>
    <div ng-controller="geek">
        First value is {{displayVal1}}<br>
        Second value is {{displayVal2}}<br><br>
        <input type="button" 
               ng-click="Check()" 
               value="Check Value">
    </div>
    <script>
        var App = angular.module("App", []);
        App.controller("geek", function ($scope) {
            var val1 = "GeeksforGeeks";
            var val2;
            $scope.displayVal1 = '';
            $scope.displayVal2 = '';
            $scope.Check = function () {
                angular.isUndefined(val1)? $scope.displayVal1 = 
                'does not exist': $scope.displayVal1 = 'Exist';
                angular.isUndefined(val2)? $scope.displayVal2 = 
                'does not exist' : $scope.displayVal2 = 'Exist';
            }
        });
    </script>
</body>
</html>


Output:

 


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