Ternary operator in AngularJS templates
JavascriptHtmlAngularjsTernary OperatorJavascript Problem Overview
How do you do a ternary with AngularJS (in the templates)?
It would be nice to use some in html attributes (classes and style) instead of creating and calling a function of the controller.
Javascript Solutions
Solution 1 - Javascript
Update: Angular 1.1.5 added a ternary operator, so now we can simply write
<li ng-class="$first ? 'firstRow' : 'nonFirstRow'">
If you are using an earlier version of Angular, your two choices are:
(condition && result_if_true || !condition && result_if_false){true: 'result_if_true', false: 'result_if_false'}[condition]
item 2. above creates an object with two properties. The array syntax is used to select either the property with name true or the property with name false, and return the associated value.
E.g.,
<li class="{{{true: 'myClass1 myClass2', false: ''}[$first]}}">...</li>
or
<li ng-class="{true: 'myClass1 myClass2', false: ''}[$first]">...</li>
$first is set to true inside an ng-repeat for the first element, so the above would apply class 'myClass1' and 'myClass2' only the first time through the loop.
With ng-class there is an easier way though: ng-class takes an expression that must evaluate to one of the following:
- a string of space-delimited class names
- an array of class names
- a map/object of class names to boolean values.
An example of 1) was given above. Here is an example of 3, which I think reads much better:
<li ng-class="{myClass: $first, anotherClass: $index == 2}">...</li>
The first time through an ng-repeat loop, class myClass is added. The 3rd time through ($index starts at 0), class anotherClass is added.
ng-style takes an expression that must evaluate to a map/object of CSS style names to CSS values. E.g.,
<li ng-style="{true: {color: 'red'}, false: {}}[$first]">...</li>
Solution 2 - Javascript
Update: Angular 1.1.5 added a ternary operator, this answer is correct only to versions preceding 1.1.5. For 1.1.5 and later, see the currently accepted answer.
Before Angular 1.1.5:
The form of a ternary in angularjs is:
((condition) && (answer if true) || (answer if false))
An example would be:
<ul class="nav">
<li>
<a href="#/page1" style="{{$location.path()=='/page2' && 'color:#fff;' || 'color:#000;'}}">Goals</a>
</li>
<li>
<a href="#/page2" style="{{$location.path()=='/page2' && 'color:#fff;' || 'color:#000;'}}">Groups</a>
</li>
</ul>
or:
<li ng-disabled="currentPage == 0" ng-click="currentPage=0" class="{{(currentPage == 0) && 'disabled' || ''}}"><a> << </a></li>
Solution 3 - Javascript
For texts in angular template (userType is property of $scope, like $scope.userType):
<span>
{{userType=='admin' ? 'Edit' : 'Show'}}
</span>
Solution 4 - Javascript
This answer predates version 1.1.5 where a proper ternary in the $parse function wasn't available. Use this answer if you're on a lower version, or as an example of filters:
angular.module('myApp.filters', [])
.filter('conditional', function() {
return function(condition, ifTrue, ifFalse) {
return condition ? ifTrue : ifFalse;
};
});
And then use it as
<i ng-class="checked | conditional:'icon-check':'icon-check-empty'"></i>
Solution 5 - Javascript
While you can use the condition && if-true-part || if-false-part-syntax in older versions of angular, the usual ternary operator condition ? true-part : false-part is available in Angular 1.1.5 and later.
Solution 6 - Javascript
There it is : ternary operator got added to angular parser in 1.1.5! see the changelog
Here is a fiddle showing new ternary operator used in ng-class directive.
ng-class="boolForTernary ? 'blue' : 'red'"
Solution 7 - Javascript
<body ng-app="app">
<button type="button" ng-click="showme==true ? !showme :showme;message='Cancel Quiz'" class="btn btn-default">{{showme==true ? 'Cancel Quiz': 'Take a Quiz'}}</button>
<div ng-show="showme" class="panel panel-primary col-sm-4" style="margin-left:250px;">
<div class="panel-heading">Take Quiz</div>
<div class="form-group col-sm-8 form-inline" style="margin-top: 30px;margin-bottom: 30px;">
<button type="button" class="btn btn-default">Start Quiz</button>
</div>
</div>
</body>
Button toggle and change header of button and show/hide div panel. See the Plunkr
Solution 8 - Javascript
if anyone is still working on legacy code like I'm you can also achieve this using a ternary operator inside ng-style like so:
<li ng-style="{'color': connected ? '#008000' : '#808080'}"></li>