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How to check the existence of key in an object using AngularJS ?
  • Last Updated : 14 Oct, 2020

Given an object containing (key, value) pair and the task is to check whether a key exists in an object or not using AngularJS.

Approach: The approach is to use the in operator to check whether a key exists in object or not. In first example the key “Prop_1” is input and it exists in the object. In the second example the user can check which key they want to check for existence.

Example 1:




<!DOCTYPE HTML>
<html>
  
<head>
    <script src=
"//ajax.googleapis.com/ajax/libs/angularjs/1.2.13/angular.min.js">
    </script>
  
    <script>
        var myApp = angular.module("app", []);
        myApp.controller("controller", function ($scope) {
            $scope.obj1 =
                { "Prop_1": 1, "Prop_2": 2, "Prop_3": 3 };
            $scope.res = '';
            $scope.textval = "Prop_1";
            $scope.checkK = function () {
                var txtVal = $scope.textval;
                if (!(txtVal in $scope.obj1)) {
                    $scope.res = "Key not Exists.";
                } else {
                    $scope.res = "Key Exists";
                }
            }
        });
    </script>
</head>
  
<body style="text-align:center;">
    <h1 style="color:green;">
        GeeksForGeeks
    </h1>
    <p>
        Check if a key exists in 
        an object in AngularJS
    </p>
    <div ng-app="app">
        <div ng-controller="controller">
            Object - {{obj1}}<br><br>
            Enter the key: <input type="text" 
                    ng-model="textval">
            <br><br>
            <button ng-click="checkK()">
                Check here</button>
            <br><br>
            {{res}}<br>
        </div>
    </div>
</body>
  
</html

Output:



Example 2:




<!DOCTYPE HTML>
<html>
  
<head>
    <script src=
"//ajax.googleapis.com/ajax/libs/angularjs/1.2.13/angular.min.js">
    </script>
  
    <script>
        var myApp = angular.module("app", []);
        myApp.controller("controller", function ($scope) {
            $scope.obj1 =
                { "Prop_1": 1, "Prop_2": 2, "Prop_3": 3 };
            $scope.res = '';
            $scope.textval = "";
            $scope.checkK = function () {
                var txtVal = $scope.textval;
                if (!(txtVal in $scope.obj1)) {
                    $scope.res = "Key not Exists.";
                } else {
                    $scope.res = "Key Exists";
                }
            }
        });
    </script>
</head>
  
<body style="text-align:center;">
    <h1 style="color:green;">
        GeeksForGeeks
    </h1>
    <p>
        Check if a key exists in 
        an object in AngularJS
    </p>
    <div ng-app="app">
        <div ng-controller="controller">
            Object - {{obj1}}<br><br>
            Enter the key: <input type="text" 
                    ng-model="textval">
            <br><br>
            <button ng-click="checkK()">
                Check here</button>
            <br><br>
            {{res}}<br>
        </div>
    </div>
</body>
  
</html>   

Output:




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