angular.extend方法和merge方法

AngularJs的angular.extend()方法可以把一个或多个对象中的方法和属性扩展到一个目的对象中，使得这个对象拥有其他对象相同的方法和属性，如下图所示。

angular.extends()方法的第一个参数是要被扩展的对象，后面可以传入一个或多个对象。

如果想要保存一个对象的状态，除了可以调用angular.copy()方法外，还可以把一个空对象｛｝作为第一个对象传入。

但要注意的是，angular.extends()是非递归的，也就是说：如果扩展的属性中有对象，那么二者同时引用同一个对象！

下面这个例子证实了这个说法：

<!DOCTYPE html>
<html ng-app="extendApp">
<head>
    <meta charset="UTF-8">
    <title></title>

    <script src="../js/angular.js"></script>
    <script type="text/javascript">
        angular.module("extendApp", [])
                .controller("extendController", function($scope)
                {
                    $scope.baby =
                    {
                        cry : function()
                        {
                            console.log("I can only cry!");
                        }
                    }

                    $scope.adult =
                    {
                        earn : function()
                        {
                            console.log("I can earn money!");
                        },

                        lover:
                        {
                            love:function()
                            {
                                console.log("I love you!");
                            }
                        }
                    }

                    $scope.human = {}

                    $scope.hehe = "hehe ";

                    $scope.extend = function()
                    {
                        angular.extend($scope.human, $scope.baby, $scope.adult);
                        $scope.human.cry();
                        $scope.human.earn();

                        <!-- 注意，这里修改了lover对象的love()方法，由于extends()方法不是深复制的，$scope.human
                         和$scope.adult其实引用的是同一个对象-->
                        $scope.human.lover.love = function()
                        {
                            console.log("I hate you!");
                        }

                        <!-- 这两行都会输出“I hate you !"，可怜的adult对象,
                        他把自己的lover分享给了human! -->
                        $scope.human.lover.love();
                        $scope.adult.lover.love();


                    }
                });
    </script>
</head>
<body>

<div ng-controller="extendController">

    <button ng-click="extend()">点击我！</button>

</div>
</body>
</html>

　　控制台的打印结果如下：

I can only cry!
I can earn money!
I hate you!
I hate you!

merge

angular.merge(dst, src);
说明：

和extend的区别就是merge是深拷贝。
如下图，在extend中，src中的c对象会被src2中的c对象覆盖；在merge中，会将两个源中的对象都拷贝，如src中c对象中的d，如果两个源中存在相同对象，并且相同对象中存在相同key，key对应的值会被后者覆盖。

代码：

$scope.src = {
    a: 'A',
    b: 'B',
    c: {
        d: 'D',
        e: {
            f: 'F'
        }
    }
};
$scope.src2 = {
    c: {
        src2: 'D',
        e: {
            src2: 'src2',
            f: 'FFFFF'
        }
    }
};
$scope.dest = {
    A: 'a'
};
$scope.temp = angular.merge($scope.dest, $scope.src, $scope.src2);
$scope.change = function(){
    $scope.temp.A = 'changed';
}

效果：

src: {"a":"A","b":"B","c":{"d":"D","e":{"f":"F"}}}
src2: {"c":{"src2":"D","e":{"src2":"src2","f":"FFFFF"}}}
temp: {"A":"a","a":"A","b":"B","c":{"d":"D","e":{"f":"FFFFF","src2":"src2"},"src2":"D"}}
dest: {"A":"a","a":"A","b":"B","c":{"d":"D","e":{"f":"FFFFF","src2":"src2"},"src2":"D"}}
点击button后

src: {"a":"A","b":"B","c":{"d":"D","e":{"f":"F"}}}
src2: {"c":{"src2":"D","e":{"src2":"src2","f":"FFFFF"}}}
temp: {"A":"changed","a":"A","b":"B","c":{"d":"D","e":{"f":"FFFFF","src2":"src2"},"src2":"D"}}
dest: {"A":"changed","a":"A","b":"B","c":{"d":"D","e":{"f":"FFFFF","src2":"src2"},"src2":"D"}}