How to check the existence of key in an object using AngularJS ?
Given an object containing a (key, value) pair and the task is to check whether a key exists in an object or not using AngularJS. In order to check the existence of a key in an object, we will create an object having properties in the form of a key: value pair. Define a temporary variable that will hold the initial key of an object. Create a function expression that will be utilized to check whether the temporary variable that holds an initial key, exists or not in the given object, by comparing them.
Approach: The approach is to use the in operator to check whether a key exists in an object or not. In the 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: In this example, the key "Prop_1" is input and checking whether it exists in the object or not.
<!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.textval = "Prop_1";
$scope.checkK = function() {
var txtVal = $scope.textval;
if(!(txtVal in $scope.obj1)) {
$scope.res = "Key not Exists.";
} else {
$scope.res = "Key Exists";
}
}
});
</script>
</head>
<body style="text-align:center;">
<h1 style="color:green;">
GeeksforGeeks
</h1>
<h3>
Check if a key exists in
an object in AngularJS
</h3>
<div ng-app="app">
<div ng-controller="controller"> Object - {{obj1}}
<br><br>
Enter the key:
<input type="text" ng-model="textval">
<br><br>
<button ng-click="checkK()">
Check here
</button>
<br><br> {{res}}
</div>
</div>
</body>
</html>
Output:
Example 2: In this example, the user will check which key they want to check for existence in the given object.
<!DOCTYPE HTML>
<html>
<head>
<script src=
"//ajax.googleapis.com/ajax/libs/angularjs/1.2.13/angular.min.js">
</script>
<script>
var myApp = angular.module("app", []);
myApp.controller("controller", function($scope) {
$scope.obj1 = {
"Prop_1": 1,
"Prop_2": 2,
"Prop_3": 3
};
$scope.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>
<h3>
Check if a key exists in
an object in AngularJS
</h3>
<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}}
</div>
</div>
</body>
</html>
Output:
