一、用function实现：
function Person(name) { this.name = name; } Person.prototype.getName = function() { return this.name; } function Author(name, books) { this.inherit=person; this.inherit(name); this.books = books; } var au=new Author("dororo","Learn much"); au.name
或者同等效力的：
function Person(name) { this.name = name; } Person.prototype.getName = function() { return this.name; } function Author(name, books) { Person.call(this, name); this.books = books; } var au=new Author("dororo","Learn much"); au.getName
由于这只是将this作为参数，调用父类Person的构造函数，把赋予父类的所有域赋予Author子类，所以任何父类Person构造函数之外的定义的域（原型prototype），子类都不会继承。所以上面例子中，au.getName将是没有被定义的（undefined），因为getName是在Person的原型对象中定义的。
而且，子类的构造函数要在定义自己的域之前调用父类构造函数，免得子类的定义被父类覆盖掉。也就是说，Author定义属性book要在Person.call之后，否则会被Person中属性覆盖。同时，在子类中也最好不要用prototype来定义子类的函数域，因为在一个子类被new，实例化之后就要执行prototype，然后才是调用父类的构造函数，这样也容易被父类的属性覆盖掉。
二、用prototype实现：
function Person(name) { this.name = name; } Person.prototype.getName = function() { return this.name; } function Author(name, books) { this.books = books; } Author.prototype=new Person(name); Author.prototype.constructor=Author; Author.prototype.getBooks = function() { return this.books; } var au1=new Author("dororo1","Learn much"); var au2=new Author("dororo2","Learn less"); alert(au1.getName()); alert(au2.getName());
这种方法避免了function实现中，无法继承prototype的问题。因为 Author.prototype=new Person(name);new Person（）实例会调用Person构造和原型的所有属性。但是缺点是已经实例化了Author.prototype。所以当子类实例化的时候，所有非基本数据类型都是reference copy。所以上面例子中，无论实例au1,还是au2返回的值都是dororo1.
三、用“混合”实现
function Person(name) { this.name = name; } Person.prototype.getName = function() { return this.name; } function Author(name, books) { this.base = new Person(name); for(var key in this.base){ if(!this[key]){ this[key]=this.base[key]; } } this.book=books; } var au1=new Author("dororo1","work"); var au2=new Author("dororo2","play"); alert(au1.getName()); alert(au2.getName()); au1.book; au2.book;
属于扩展，把父类的所有域都拷贝到子类。完全没有上述两方面的问题。
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"> <head> <title></title> </head> <body> <script type="text/javascript">
// ------------------------继承的第一种方式：对象冒充-----------------------------
function Parent(name) { this.name = name; this.showInfo = function () { document.write(name); document.write("</br>"); } }
function Children(name, pwd) {//下面三行代码实现了子对象和父对象指向同一个引用//关键的代码this.method = Parent;this.method(name);delete this.method;
this.pwd = pwd;this.showMsg = function () {document.write(this.pwd);document.write("</br>");}}
var parent = new Parent("John");var child = new Children("Bob", 123);
parent.showInfo();child.showInfo();child.showMsg();
document.write("");document.write("</br>");
//call方法，是function里的一个方法。
//------------------------call方法简单示例-------------------------------
function test(str) {document.write(this.name + "," + str+"</br>");}
var person = new Object();person.name = "anllin";
//相当于调用了test方法test.call(person, "welcome"); //将person赋给了test里的this。
document.write("");document.write("</br>");
//--------------------继承的第二种方式，call方法------------------------------
function Father(name) {this.name = name;this.showName = function () {document.write(this.name + "</br>");}}
function Sub(name, pwd) {//关键的代码Father.call(this, name);
this.pwd = pwd;this.showPwd = function () {document.write(this.pwd + "<br>");}}
var father = new Father("Father");var sub = new Sub("Sub", 123456);father.showName();sub.showName();sub.showPwd();
document.write("");document.write("</br>");
//--------------------继承的第三种方式，apply方法------------------------------
function Mother(name) {this.name = name;this.showName = function () {document.write(this.name + "</br>");}}
function Daugther(name, pwd) {//关键的代码Mother.apply(this, new Array(name));
this.pwd = pwd;this.showPwd = function () {document.write(this.pwd + "<br>");}}
var mother = new Father("Mother");var daugther = new Sub("Daugther", 654321);mother.showName();daugther.showName();daugther.showPwd();
document.write("");document.write("</br>");
//--------------------继承的第四种方式，prototype chain方式------------------------------
//缺点：无法给构造函数传参数。
function Human(){ }
Human.prototype.name = "human";Human.prototype.showName = function () {document.write(this.name+"<br>");}
function Student() { }
//关键的代码Student.prototype = new Human();
Student.prototype.password = 456789;Student.prototype.showPwd = function () {document.write(this.password + "<br>");}
var human = new Human();var student = new Student();student.name = "student";human.showName();student.showName();student.showPwd();
document.write("");document.write("</br>");
//--------------------继承的第五种方式，混合方式------------------------------
function FatherClass(name) {this.name = name;}
FatherClass.prototype.showName = function () {document.write(this.name + "<br>");}
function SubClass(name, pwd) {
//关键的代码
FatherClass.call(this,name);this.pwd = pwd;}
//关键的代码
SubClass.prototype = new FatherClass;
SubClass.prototype.showPwd = function () {document.write(this.pwd + "<br>");}
var f = new FatherClass("FatherClass");var s = new SubClass("SubClass", 45678);f.showName();s.showName();s.showPwd();
</script> </body> </html>