AngularJS toggle class using ng-class

Question

AngularJS toggle class using ng-class

I am trying to toggle the class of an element using ng-class

<button class="btn">
  <i ng-class="{(isAutoScroll()) ? 'icon-autoscroll' : 'icon-autoscroll-disabled'}"></i>
</button>

isAutoScroll():

$scope.isAutoScroll = function()
{
    $scope.autoScroll = ($scope.autoScroll) ? false : true;
    return $scope.autoScroll;
}

Basically, if $scope.autoScroll is true, I want ng-class to be icon-autoscroll and if its false, I want it to be icon-autoscroll-disabled

What I have now isn't working and is producing this error in the console

Error: Lexer Error: Unexpected next character at columns 18-18 [?] in expression [{(isAutoScroll()) ? 'icon-autoscroll' : 'icon-autoscroll-disabled'}].

How do I correctly do this?

EDIT

solution 1: (outdated)

<button class="btn" ng-click="autoScroll = !autoScroll">
  <i ng-class="{'icon-autoscroll': autoScroll, 'icon-autoscroll-disabled': !autoScroll}"></i>
</button>

EDIT 2

solution 2:

I wanted to update the solution as Solution 3 provided by Stewie should be the one used. It is the most standard when it comes to ternary operator (and to me easiest to read). The solution would be

<button class="btn" ng-click="autoScroll = !autoScroll">
  <i ng-class="autoScroll ? 'icon-autoscroll' : 'icon-autoscroll-disabled'"></i>
</button>

translates to:

if (autoScroll == true) ? //use class 'icon-autoscroll' : //else use 'icon-autoscroll-disabled'

javascript
angularjs

Answer 1

How to use conditional in ng-class:

Solution 1:

<i ng-class="{'icon-autoscroll': autoScroll, 'icon-autoscroll-disabled': !autoScroll}"></i>

Solution 2:

<i ng-class="{true: 'icon-autoscroll', false: 'icon-autoscroll-disabled'}[autoScroll]"></i>

Solution 3 (angular v.1.1.4+ introduced support for ternary operator):

<i ng-class="autoScroll ? 'icon-autoscroll' : 'icon-autoscroll-disabled'"></i>

Plunker

Answer 2

As alternate solution, based on javascript logic operator '&&' which returns the last evaluation, you can also do this like so:

<i ng-class="autoScroll && 'icon-autoscroll' || !autoScroll && 'icon-autoscroll-disabled'"></i>

It's only slightly shorter syntax, but for me easier to read.

Answer 3

Add more than one class based on the condition:

<div ng-click="AbrirPopUp(s)" 
ng-class="{'class1 class2 class3':!isNew, 
           'class1 class4': isNew}">{{ isNew }}</div>

Apply: class1 + class2 + class3 when isNew=false,

Apply: class1+ class4 when isNew=true