<!DOCTYPE html> <html lang="en" ng-app> <head> <meta charset="UTF-8"> <title>Document</title> <script type="text/javascript" src="js/angular-1.3.0.js"></script> <script> function shop($scope){ $scope.items = { "name":"apple", "price":"5", "quantity":"5", "fre":"10" }; $scope.sum = function (){ return $scope.items.price * $scope.items.quantity; }; $scope.$watch($scope.sum,function(newVal,oldVal){ $scope.items.fre = newVal >= 100 ? 0 : 10; }); } </script> </head> <body ng-controller="shop"> <div > <span>{{items.name}}</span><br/> <span>{{items.price}}</span><br/> <input type="text" ng-model="items.quantity"><br/> <span>{{items.fre | currency:'¥' }}</span><br/> <span>{{sum() + items.fre | currency:'¥'}}</span> </div> </body> </html>