JavaScript笔记 - 对象继承的几种方式
1)对象冒充
2)call方式
3)apply方式
4)原型链
5)混合方式
1)对象冒充
- function People(name, age) {
- this.name = name;
- this.age = age;
- this.speak = function() {};
- };
- function Chinese(name) {
- this.inherit = People; //冒充,会继承所有方法
- this.inherit(name, age); //继承,必须指定继承的属性
- delete this.inherit; //删除继承
- //需要定义的新方法、属性或者“重载”的方法在删除inherit后
- this.speak = function() {};
- }
2)call方式
封装了方式1的“经典三句”,一样的效果。
- function Sub(param1, param2) {
- Super1.call(this, param1);
- Super2.call(this, param2);
- };
3)apply方式
同call一样,只是使用方式不同:Super.apply(对象,参数数组);
- function Sub(param1, param2, param3) {
- Super1.apply(this, new Array(param1, param2);
- Super2.apply(this, new Array(param3);
- };
4)原型链方式
父类不用构造函数创建,而是原型方式
缺点:不能传递参数,不支持多重继承
- function Super() {};
- Super.prototype.param1 = "sth.";
- Super.prototype.foo = function() {};
- function Sub() {};
- Sub.prototype = new Super();
- usage: var aSub = new Sub; Sub.foo();
5)混合方式:
a)用构造函数定义新的属性,用call或apply继承属性。
b)用原型方式定义新的方法,用原型链继承方法。
- function Super(param1) {
- this.param1 = param1;
- Super.prototype.foo = function() {};
- };
- function Sub(param1, param2) {
- Super.call(this, param1);
- this.param2 = param2; //别用this.prototype.param2 = param2;
- Sub.prototype = new Super();
- Sub.prototype.bar = function() {};
- };
js继承探讨
每当我们说到js的继承时,在您的脑袋的第一反应就是prototype原型机制来实现。但是您是否使用过其他的方法来实现继承呢,或者您是否了解其他实现方式及各种不同的继承实现机制的优缺点呢?
好了,下面我们就来看看几种比较常见的继承实现吧。
1、 prototype方式
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
24
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
25
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
26
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
27
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
28
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
29
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
30
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
这种方式最为简单,只需要让一个类的prototype为被继承的一个实例就ok,然后直接使用BaseClass的方法。
prototype属性是啥意思呢?prototype即为原型,每一个对象(由function 定义出来)都有一个默认的原型属性,该属性是个对象类型。并且该默认属性用来实现链的向上攀查。意思就是说,如果某个对象的属性不存在,那个将通过prototype属性对应的对象的来查找该对象的属性。如果prototype查找不到呢? js会自动地找prototype的prototype属性对应的对象来查找,这样就通过prototype一直往上索引攀查,直到查找到了该属性或者prototype最后为空("undefined");
例如:上例中的instance.ToString()方法。js会先在instance实例中查找是否有ToString()方法,因为没有,所以查找Derived.prototype属性,而prototype 为 NewClass的一个实例,该实例有ToString()方法,于是调用成功;同样给instance 的 name 属性赋值时也是查找prototype来实现的。
注意,每一个对象得prototype都默认对应一个object对象,但是该对象不等于Object;如何验证呢?看如下代码:
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
这段代码的result 所得值为 false;
以下几个需要注意:
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2、apply方式
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
24
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
25
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
26
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
27
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
28
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
29
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
30
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
31
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
32
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
在这种方式下,我们最需要理解的就是apply函数的作用。
该方法普遍的解释为用A方法去替换B方法。第一个参数为B方法的对象本身,第二个参数为一个数组,该数组内的值集合为需要传递给A方法对应的参数列表,如果参数为空,即没有参数传递,则通过 new Array() 来传递,null无效。
一般的方式为:
但是在本例当中,apply方法执行了两步操作。
第一:将BaseClass以apply传递的Array数组作为初始化参数进行实例化。
第二:将新生成的实例对象的所有属性(name,age,ToString方法)复制到 instance实例对象。这样就实现了继承。
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3、call+prototype 方式
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
24
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
25
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
26
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
27
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
28
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
29
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
30
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
31
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
32
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
33
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
其实,call函数和apply方式有很类似的作用,都是用A方法去替换B方法,但是参数传递不一样,call方法的第一个参数为B方法的对象本身,和面的参数列不用Array对象包装,直接依次传递就可以。
为什么作用类似,call方式的实现机制却要多一条 Derived.prototype = new BaseClass(); 语句呢?那是因为call方法只实现了方法的替换而没有作对象属性的复制操作。
call方法实际上是做了如下几个操作:
例:
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
则 this.fooB.call(this,"sorry")执行了如下几个操作:
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
其实,google Map API 的继承就是使用这种方式。大家可以下载的参考参考(maps.google.com)。
4、prototype.js中的实现方式
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
24
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
25
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
26
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
27
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
28
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
29
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
30
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
31
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
32
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
33
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
34
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
35
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
36
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
37
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
38
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
39
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
40
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
41
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
42
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
43
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
44
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
45
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
46
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
47
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
48
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
49
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
该方式,实际上是显式的利用了apply的原理来实现继承。先 var temp = new BaseClass(),再将 temp 的属性遍历复制到Derived.prototype中。for (property in source) 表示遍历某个对象的所有属性。但是私有属性无法遍历。例:
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
24
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
25
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
26
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
27
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
28
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
29
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
30
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
31
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
32
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
33
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
34
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
35
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
输出为 "name age"而没有"innerString" 和 "innerToString()";具体原理,以后有机会可以解释(包括私有变量,私有函数,私有函数的变量可访问性等等)。上面总结了种种继承方式的实现。但是每种方法都有其优缺点。
第一种方式,如何实现如下需求,需要显示 "3zfp__100";
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
24
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
25
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
26
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
27
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
28
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
29
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
30
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
31
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
我们通过运行可以发现,实际上输出的是 "undefined__undefined"。也就是说name和age没有被赋值。
oh,my god!天无绝人之路。第二和第三种方法可以实现,具体如下:
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
24
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
25
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
26
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
27
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
28
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
29
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
30
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
31
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
32
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
33
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
34
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
35
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
36
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
37
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
38
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
39
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
40
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
41
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
42
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
43
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
44
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
45
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
46
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
47
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
48
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
49
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
50
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
51
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
52
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
53
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
54
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
55
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
56
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
57
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
58
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
59
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
60
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
61
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
62
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
63
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
64
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
65
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
66
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
67
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
68
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
69
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
70
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
但是用apply方法也还是有缺点的,为什么?在js中,我们有个非常重要的运算符就是"instanceof",该运算符用来比较某个对向是否为某种类型。对于继承,我们除了是属于 Derived类型,也应该是BaseClass类型,但是。apply方式返回值为false((instance instanceof BaseClass) == false).由于prototype.js使用了类似apply的方式,所以也会出现这个问题。
啊,终极方法就是 call+prototype方式了,还是google牛X。您可以试一下是否正确((instance instanceof BaseClass) == true)。
最后,就是多重继承了,由于js中prototype只能对应一个对象,因此无法实现真正意义上的多重继承。有一个js库模拟了多重继承,但是该库也额外重写了 instanceOf 方法,用 _instanceOf和_subclassOf 函数来模拟判断。该库的名字叫modello.js,感兴趣的可以搜索下载。