(function(angular) {
            'use strict';
            angular.module('myApp', [])
                    .controller('firstController', function firstController($scope,$timeout) {
                        $scope.firstNum = 1;
                        $scope.secondNum = 1;
                        $scope.doMySum = function(){
                                var fn = angular.isNumber($scope.firstNum)?$scope.firstNum:0;
                                var sn = angular.isNumber($scope.secondNum)?$scope.secondNum:0;
                                return fn+sn;
                            }
                        $timeout(function(){
                            $scope.firstNum = 10;
                        },2000);

                        $scope.$watch('doMySum()',function(newValue, oldValue){
                            if(newValue == 100){
                                alert('ok');
                            }
                        });
                    });
        })(window.angular);
    



   
        
       +
       ={{doMySum()}}