The element passed to `addClass` should be a jQuery/jqLite element, so it's always an ArrayLike object, making `forEach` [treat is as an array instead of an object](https://github.com/angular/angular.js/blob/3b3e89d5d6e7878bd8163631536e761f84255015/src/Angular.js#L146-L148) 

So `forEach`'ing it allows you to iterate over each DOM node inside the collection.

Maybe a change in the naming of the variable would make this more clear? 
That's related to style more than anything else