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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