Your scenario sounds like it could use a custom filter.
Something close to:
custom filter:
angular.module('myApp', []).filter('mySumFilter', function() {
return function(items, param1, param2) {
return //perform sum items object in case of necessary use params to narrow your operation
};
});
and in your html
<div> {{ salaryArray |mySumFilter:'salary': 2"}} </div>
Of course you could extend it and perform the actions that are more suited to your app needs.