How to detect current state within directive

Also you can use ui-sref-active directive:

<ul>
  <li ui-sref-active="active" class="item">
    <a href ui-sref="app.user({user: 'bilbobaggins'})">@bilbobaggins</a>
  </li>
  <!-- ... -->
</ul>

Or filters: "stateName" | isState & "stateName" | includedByState

If you are using ui-router, try $state.is();

You can use it like so:

$state.is('stateName');

Per the documentation:

$state.is ... similar to $state.includes, but only checks for the full state name.

Update:

This answer was for a much older release of Ui-Router. For the more recent releases (0.2.5+), please use the helper directive ui-sref-active. Details here.

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Original Answer:

Include the $state service in your controller. You can assign this service to a property on your scope.

An example:

$scope.$state = $state;

Then to get the current state in your templates:

$state.current.name

To check if a state is current active:

$state.includes('stateName'); 

This method returns true if the state is included, even if it's part of a nested state. If you were at a nested state, user.details, and you checked for $state.includes('user'), it'd return true.

In your class example, you'd do something like this:

ng-class="{active: $state.includes('stateName')}"