js定义对象的方法和继承的方法

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定义对象的方法

基于已有对象扩充其对象和方法(只适合于临时的生成一个对象)：

    var obj = new Object();    //两种增加对象属性的方法    obj.username = "user";    obj["password"] = 123;    //增加方法    obj.show  =function(username,password){            this.username = username;            this.password = password;            alert(this.username+":"+this.password);    }    //删除属性    delete obj.username;

2.开发最为常见的定义对象方式

var obj = {username:"root",password:123};        alert(obj.username+":"+obj.password);

有方法的：

var obj = {username:"root",password:54,            show :function(){                alert(this.username+":"+this.password);            }    };    obj.show();

3.工厂模式(无参)

function createObject(){            var obj = new Object();            obj.username = "root";            obj.password = 123;            obj.show = function(){                alert(this.username+":"+this.password);            };            return obj;        }        var obj1 = createObject();        obj1.username = "fate";        var obj2 = createObject();        obj1.show();        obj2.show();

4.工厂模式（带参数）

function createObject(username,password)        {            var obj = new Object();            obj.username = username;            obj.password = password;            obj.show = function()            {                alert(this.username +":"+ this.password);            };            return obj;        }        var obj = createObject("fate","1234");        obj.show();

让方法被多个对象共享：

function createObject(username,password)        {            var obj = new Object();            obj.username = username;            obj.password = password;            obj.show = show;            return obj;        }        //把方法创建到对象工厂外面，被多对象共享        var show = function()        {            alert(this.username +":"+ this.password);        };        var obj1 = createObject("小明","1234");        var obj2 = createObject("张三","4564");        obj1.show();        obj2.show();

5.构造函数方法
无参：

        function Person(){            //在执行第一行代码前，js引擎会为我们生成一个对象            this.username = "小明";            this.password = "1564";            this.show = function(){                alert(this.username+":"+this.password);            }            //此处隐藏一个return语句，用于把生成的对象返回        }        //在这里new一个对象        var p = new Person();        p.show();

有参：

    function Person(username,password){            //在执行第一行代码前，js引擎会为我们生成一个对象            this.username = username;            this.password = password;            this.show = function(){                alert(this.username+":"+this.password);            }            //此处隐藏一个return语句，用于把生成的对象返回        }        //在这里new一个对象        var p = new Person("小红","464641");        p.show();

6.原型（ prototype）方式

    function Person(){    }    //用prototype添加对象的属性和方法    Person.prototype.username = "张三";    Person.prototype.password = "1389";    Person.prototype.show = function(){        alert(this.username+":"+this.password);    };    //new对象    var person1 =  new Person();    var person2 = new Person();    person1.username = "夏天";    person1.show();    person2.show();

prototype增加的属性为数组：

    function Person(){    }    //用prototype添加对象的属性和方法    Person.prototype.username = new Array();    Person.prototype.password = "1389";    Person.prototype.show = function(){        alert(this.username+":"+this.password);    };    //new对象    var person1 =  new Person();    var person2 = new Person();    person1.username = "夏天";    person2.username = "林";    person1.password = "168";    person1.show();    person2.show();

缺点：：单纯使用原型方式创建对象，无法给对象传参数，只能通过创建对象后再去改变属性的值
7. 原型+构造函数方式（各个对象之间互不干扰，各个对象共享一个方法）

    function Person(password){        this.username = new Array();        this.password = password;    }    Person.prototype.show = function(){        alert(this.username+":"+this.password);    };    var p1 = new Person("5644");    var p2 = new Person("111111");    p1.username.push("小白");    p2.username.push("小黑");    p1.show();    p2.show();

8.动态原型方式：在构造函数中通过标质量让所有对象共享一个方法，而每个对象拥有自己的属性。

function Person(){        this.username = "小白";        this.password = "156";        //做一个判断标志，让方法只产生一次        if(typeof Person.flag == "undefined"){//这里只要Person.flag不等于Undefined，其他的值都为true            Person.prototype.show = function(){                alert(this.username+":"+this.password);        };            Person.flag = true;        }    }        var p1 = new Person();        var p2 = new Person();        p1.username = "大白";        p1.show();        p2.show();

javacript继承的方法

对象冒充

//父对象    function Parent(username){        this.username = username;        this.show = function(){            alert(this.username);        };    }    //子对象    function Child(username,password){        //下面三行为关键代码        this.method = Parent;        this.method(username);        delete this.method;        //子类特有的属性和方法        this.password = password;        this.showInfo = function(){            alert(this.password);        };    }    var parent = new Parent("小红");    var child = new Child("小明","321345");    parent.show();    //子类能够调用父类的属性和方法    child.username ="大白";    child.show();    child.showInfo();

2.call的方法方式(父类引用在子类中调用call方法，第一个参数传代表子类的this，后面根据父类参数依次传)

    //父类        function Parent(username){            this.username = username;            this.show = function(){                alert(this.username);            };        }    //子类    function Child(username,password){        //父类对象调用call方法，把代表子类的this传过去        Parent.call(this, username);        this.password = password;        this.showInfo = function(){            alert(this.password);        };    }    var parent = new Parent("小红");    var child = new Child("小白","15");    parent.show();    //子类继承父类的方法    child.show();    child.showInfo();

3.apply方法

//父类    function Parent(username,age){        this.username = username;        this.age = age;        this.show = function(){            alert(this.username);        };    }//子类function Child(username,password,age){//子类的参数要包含父类的所有参数    //父类对象调用apply方法，把代表子类的this传过去,后面父类对应的所有参数都依次添加到数组中    Parent.apply(this, new Array(username,age));    this.password = password;    this.showInfo = function(){        alert(this.password);    };}var parent = new Parent("小红");var child = new Child("小白白","15");parent.show();//子类继承父类的方法child.age = "24";child.show();child.showInfo();

4.原型链方式（无法给构造方法传参）

    //父类    function Parent(){    }    Parent.prototype.username = "小白";    Parent.prototype.show = function(){        alert(this.username);    };    //子类    function Child(){    }    //关键代码，这样子类就拥有了父类用prototype添加的属性和方法，不是prototype添加的子类没有继承    Child.prototype  = new Parent();    Child.prototype.password = "484984";    Child.prototype.showInfo = function(){        alert(this.password);    };    var child = new Child();    //子类继承了父类的属性和方法    child.username = "小小";    child.show();    child.showInfo();

5.混合模式（推荐使用）

//父类        function Parent(username){            this.username = username;        }        //给父类添加方法        Parent.prototype.show = function(){            alert(this.username);        };        //让子类拥有了父类的username        function Child(username,password){            Parent.call(this,username);            this.password = password;        }        //让子类拥有了父类用prototype添加的show()方法        Child.prototype = new Parent();        Child.prototype.showInfo = function(){            alert(this.password);        };        var child = new Child("小白","748974854");        child.show();        child.showInfo();

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