父级:
function Parent(name){
this.name=name;
}
Parent.prototype.sayHello=function(){
console.log("Hello,"+this.name);
}原型链继承
function Kid(){};
Kid.prototype=new Parent("who");
var k=new Kid();
console.log(k.name); //who
console.log(k.sayHello()); //Hello,who弊端:创建实例时无法向父级传参
构造继承
function Kid(name){
Parent.call(this,name);
};
var k=new Kid("who");
console.log(k.name); //who
console.log(k.sayHello()); //error弊端:无法获取父级原型链属性
实例继承
function Kid(name){
var p=new Parent(name);
return p;
};
var k=new Kid("who");
console.log(k.name); //who
console.log(k.sayHello()); //Hello,who弊端:实例是父级的实例
拷贝继承
function Kid(name){
var p=new Parent(name);
for(var item in p){
Kid.prototype[item]=p[item];
}
}
var k=new Kid("who");
console.log(k.name); //who
console.log(k.sayHello()); //Hello,who弊端:太占用内存
组合继承
function Kid(name){
Parent.call(this,name);
}
Kid.prototype=new Parent();
var k=new Kid("who");
console.log(k.name); //who
console.log(k.sayHello()); //Hello,who弊端:调用了两次父类构造函数
寄生组合继承
function Kid(name){
Parent.call(this,name);
}
(function(){
var p=function(){};
p.prototype=Parent.prototype;
Kid.prototype=new p();
})()弊端:写法比较繁琐
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