Angular ng-class code - angularjs

Question

I am very new to Angular and I have this piece of code:
<nav ng-controller="navController">
<ul>
<li ng-class="{'active': location('/') || location('/homepage')}">
view puppies
</li>
</ul>
</nav>
With the corresponding controller:
obApp.controller('navController', function($scope, $location) {
$scope.location = function(loc){
if(loc == $location.path()){
return true;
}else{
return false;
}
}
})
Now everything works fine. When I'm on the homepage the list element gets the class active added to it, HOWEVER there is also the angular ng-class directive code shown in the source, like so (this is the HTML source output of the browser):
<li ng-class="{'active': location('/') || location('/homepage')}" class="active">
view puppies
</li>
Should the list element not look like: <li class="active">view puppies</li> ? Logic would dictate that it should look like it is now, because ng-controller="x" shows in the source as it is as well. However that's a hook if you will. The other one's an expression. It looks funky and I'm not sure if it's ok or not. Please, if you answer, detail your answer.

Answer 1

There is nothing wrong with your code, ng-class directive doesn't remove the attribute ng-class from the element when the expression evaluates to true, since you could have more than one expression/class in your ng-class attribute value.
Additionally if the directive did remove the attribute (ng-class) angular would have no way of knowing that you have applied that directive to the element. For example, your element had ng-if on it, it would be removed from the DOM and appended conditionally.
Example
ng-class="{'active': location('/') || location('homepage'), 'disabled': location('private'))}"

Answer 2

Such usage of ng-class is non-effective because $scope.location method will be called at least twice (for location('/') and location('homepage')) each digest loop. There could be a lot of digest loops due to balancing mechanism.
Better approach is to calculate if element is active on location change.
Controller:
$scope.$on('$locationChangeSuccess', function(){
$scope.isHomePage = location('/') || location('/homepage');
});
Markup:
<nav ng-controller="navController">
<ul>
<li ng-class="{'active': isHomePage}">
view puppies
</li>
</ul>
</nav>