Conditionally apply a class with AngularJS

Using AngularJs we can apply a class condionally on any element by using ng-class.

According to AngularJS docs on ng-class

The ng-class allows you to dynamically set a css class name on html element by data-binding an expression that represents all classes to be added.

ng-class supports an expression that must evaluate to either

1. a string of space-delimited class names, or
2. an array of class names, or
3. a map/object of class names to boolean values.

Example:

Consider you have a div element as shown below

<div class="example">
    //inner elements
</div>

Now if you want to add class named "selected" to the above div conditionally. You can add the class using below code

<div class="example" ng-class="{'selected':isActive}">
    //inner elements
</div>

The class named "selected" gets applied to the above div only if "isActive" property is true.

The result will be like below

<div class="example selected" ng-class="{'selected':isActive}">
    // inner elements
</div>

You can even directly add a property(of model) as a class. see code below

<div ng-class="model.color">
    //inner elements
</div>

if model.color is "red" class named "red" is gets applied to the div.

The result will be like below

<div class="red" ng-class="model.color">
    //inner elements
</div>

Note: 

The directive won't add duplicate classes if a particular class was already set.

When the expression changes, the previously added classes are removed and only then the new classes are added.

In this way you can apply a class conditionally using AngularJS

For more posts on AngularJS please visit : AngularJS