54

I want to dynamically add a css class to an <li> element I am looping over. The loop is like this:

<li ng-repeat="todo in todos" ng-class="{{todo.priority}}">
  <a href="#/todos/{{todo.id}}">{{todo.title}}</a>
  <p>{{todo.description}}</p>
</li>

In my todo model, I have the property priority which can be "urgent", "not-so-important" or "normal" and I just want to assign the class for each element.

I know I can do this for a boolean with something like ng-class="{'urgent': todo.urgent}" But my variable is not a boolean, but has three values. How would I do this? Note also that I do not want to use ng-style="..." since my class will alter several visual things.

Improve this question

4 Answers 4

Reset to default
94

You can simply assign a function as an expression and return proper class from there. Edit: there is also better solution for dynamic classes. Please see note below.

Snippet from view:

<div ng-class="appliedClass(myObj)">...</div>

and in the controller:

$scope.appliedClass = function(myObj) {
    if (myObj.someValue === "highPriority") {
        return "special-css-class";
    } else {
        return "default-class"; // Or even "", which won't add any additional classes to the element
    }
}

Better way of doing this

I've recently learned about another approach. You pass in an object which has properties corresponding to the classes you operate on, and the values are expressions or boolean variables. A simple example:

ng-class="{ active: user.id == activeId }"

In this case active class will be added to the element as long as user.id matches activeId from the $scope object!

Improve this answer
Sign up to request clarification or add additional context in comments.

12 Comments

More accurately, ng-class takes either an object or a string, so you can do ng-class=" 'myClass'+item.priority "
I'm an angular noob, but I think there's another good reason to use the latter method rather than the former - I think if you use a function it might not set up the proper watches, whereas if you use the attributes directly it should do so.
i was already using your second method but then ran into a wall (basically the second method isn't very useful when you have multiple/complex ways of deriving the class that should be placed.. ie stuff that demands more than simple if statement).. so +1 on method 1
There´s an 'else' option? Don´t wanna do { active: user.id == activeId } {inactive: user.id != activeId}...
@geoidesic, that's not true. The original solution ng-class="appliedClass(myObj)" generates classes dynamically based on myObj state.
|
44

If you just want to add a class, use the class attribute with interpolation:

class="priority-is-{{todo.priority}}"
Improve this answer

2 Comments

I'm wondering if this has any drawbacks? This feels wrong but I don't know why.
you may need ng-class possibly for IE or Edge to work well
10

You almost got it :)
It should be without interpolation markup ({{ and }}):

<li ng-repeat="todo in todos" ng-class="todo.priority">
...
Improve this answer

Comments

0

You can do this dynamically and with a ternary.

ng-class="service.Icon != '' ? service.Icon : 'fas fa-arrow-alt-circle-right'"

The above code will inject the class stored in Icon if it is not null and default to the second if you its not included.

This will allow for multiple classes.

The answer above where you call a function() in databound instances may cause a document consumption loop if anything in the state changes. If you were to put a console write in that, you may find your page is rendered 100 times before it stops looping.

NOTE: Don't put the object {} around it when using ternary. You will get errors.

Improve this answer

Comments

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.