AngularJS ng-class Directive

Last Updated : 01 Aug, 2022

The ng-class Directive in AngularJS is used to specify the CSS classes on HTML elements. It is used to dynamically bind classes on an HTML element. The value for the ng-class has either string, an object, or an array. It must contain more than one class name, which is separated by space, in the case of a string. If it is an object, it will contain the key-value pairs, where the key represents the class name for the class that wants to add & value represent the boolean value. If the expression inside the ng-class directive returns true then only the class is added else it is not added. If the value of ng-class is an array then it can be the combination of both strings as well as an array. It is supported by all HTML elements.

Syntax:

<element ng-class="expression"> 
    Contents... 
</element>

Example 1: This example uses the ng-class Directive to set and reset the CSS class.

HTML

<!DOCTYPE html>
<html>
 
<head>
    <title>ng-class Directive</title>
    <script src=
"https://ajax.googleapis.com/ajax/libs/angularjs/1.4.2/angular.min.js">
    </script>
    <style>
        .edit {
            color: green;
            font-size: 1.5em;
        }
    </style>
</head>
 
<body ng-app="" style="text-align:center">
    <h1 style="color:green;">
        GeeksforGeeks
    </h1>
   
    <h3>ng-class Directive</h3>
   
    <div>
        <input type="button"
               ng-click="edit=true"
               value="Style" />
        <input type="button"
               ng-click="edit=false"
               value="Reset" />
        <br><br>
            <span ng-class="{true:'edit'}[edit]">
                GeeksforGeeks
        </span> is the computer science portal for geeks.
    </div>
</body>
</html>

Output:

Example 2: This example uses the ng-class Directive to set the CSS style to the class.

HTML

<!DOCTYPE html>
<html>
 
<head>
    <title>ng-class Directive</title>
    <script src=
"https://ajax.googleapis.com/ajax/libs/angularjs/1.4.2/angular.min.js">
    </script>
    <style type="text/css">
        .index {
            color: white;
            background-color: green;
        }
    </style>
</head>
 
<body ng-app="app" style="padding:20px">
    <h1 style="color:green;">
        GeeksforGeeks
    </h1>
   
    <h3>ng-class Directive</h3>
   
    <div ng-controller="geek">
        <table>
            <thead>
                <th>Select any sorting technique:</th>
                <tr ng-repeat="i in sort">
                    <td ng-class="{index:$index==row}"
                        ng-click="sel($index)">
                         {{i.name}} 
                    </td>
                </tr>
            </thead>
        </table>
    </div>
   
    <script>
        var app = angular.module("app", []);
        app.controller('geek', ['$scope', function($scope) {
            $scope.sort = [{
                name: "Merge sort"
            }, {
                name: "Quick sort"
            }, {
                name: "Bubble sort"
            }];
            $scope.sel = function(index) {
                $scope.row = index;
            };
        }]);
    </script>
</body>
</html>