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.
<!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.
<!DOCTYPE html>
<html>
<head>
<title>angular.isUndefined() function</title>
<script src=
"http://ajax.googleapis.com/ajax/libs/angularjs/1.2.13/angular.min.js">
</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:
