listener-disposer.js

/**
 * @license MIT
 * @requires AngularJs 1.x
 * @author github.com/tincho
 * Tiny helper for listener deregistration on scope destroy
 * You'll have to wrap it up in a module/provider/whatever
 * (that's out of my focus)
 */
function LDisposer(scope) {
   var _list = [];

   function _exec(fn) { fn(); }
   function addListener(listener) {
      if (typeof listener !== "function") return;
      _list.push(listener);
   }
   addListener.destroy = _list.forEach.bind(_list, _exec);
   // fallback fake empty "scope" just to keep syntax the same
   scope = scope || { $on: function(){} };
   scope.$on('destroy', addListener.destroy);
   // this is the public API:
   return addListener;
}

usage.js

// usage
//////////////
// option A // (, for Automatic) - need to pass $scope
//////////////
var l = new LDisposer($scope);
...
l($scope.$watch("a", function() { ... }));
l($scope.$watch("b", function() { ... }));
l($scope.$on("c", function() { ... }));
// that's it. add your watchs and forget about them

//////////////
// option B // (not providing scope)
//////////////
var l = new LDisposer();
l($scope.$watch("a", function() { ... }));
l($scope.$watch("b", function() { ... }));
l($scope.$watch("c", function() { ... }));

// but with this way dont forget to: 
$scope.$on('$destroy', l.destroy);
// !!!!!!!!!!!!!!!!!!!!