js 中的对象继承
1. 对象冒充：
function Parent(username){
??? this.username = username;
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??? this.sayHello = function(){
??????? alert(this.username);
??? }
}
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function Child(username,password){
??? this.method=Parent;
??? this.method(username);
??? delete this.method;
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??? this.password=password;
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??? this.sayWorld=function(){
??????? alert(this.password);
??? }
}
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2.call 方法方式：
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function test(str1,str2){
??? alert(this.name + ", " + str1 + ", " + str2);
}
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var obj = new Object();
obj.name = "userObject";
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test.call(obj,"hello","world");
注意：这里的“hello” 和“world” 两个参数分别传递给了test方法中的str1和str2，而obj则是传给了test方法中的this。
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采用call方法来实现冒充方法的继承：
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function Parent(username){
??? this.username = username;
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??? this.sayHello = function(){
??????? alert(this.username);
??? }
}
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function Child(username,password){
????Parent.call(this,username);?
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??? this.password=password;
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??? this.sayWorld=function(){
??????? alert(this.password);
??? }
}
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3.apply 方法方式：
function Parent(username){
??? this.username = username;
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??? this.sayHello = function(){
??????? alert(this.username);
??? }
}
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function Child(username,password){
????//Parent.apply(this,[username]);
??? Parent.apply(this,new Array(username));?
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??? this.password=password;
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??? this.sayWorld=function(){
??????? alert(this.password);
??? }
}
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4.原型链方式(无法给构造函数传递参数)：
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function Parent(){}
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Parent.prototype.hello = "hello";
Parent.prototype.sayHello=function(){
??? alert(this.hello);
}
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function Child(){}
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Child.prototype = new Parent();
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Child.prototype.world = "world";
Child.prototype.sayWorld=function(){
??? alert(this.world);
}
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5.混合方式:
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function Parent(hello){
??? this.hello = hello;
}
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Parent.prototype.sayHello=function(){
??? alert(this.hello);
}
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function Child(hello,world){
??? Parent.call(this,hello);
??? this.world = world;
}
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Child.prototype = new Parent();
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Child.prototype.sayWorld=function(){
??? alert(this.world);
}
