Angular JS Change Class on ng-mouseover

<button
ng-class="{'some-class':hovering}"
ng-mouseenter="hovering=true"
ng-mouseleave="hovering=false">Add and Optimize</button>

You should use this form : ng-class

I've used something like this with success:

<button
    ng-class="{'some-class':hovering}"
    ng-mouseenter="hovering=true"
    ng-mouseleave="hovering=false">Add and Optimize</button>

Entering and leaving the button toggles $scope.hovering, and the application of some-class is contingent on the $scope.hovering scope variable being true.