function Parent(username){  this.username = username;  this.hello = function(){   alert(this.username);  }}function Child(username,password){  //通過(guò)以下3行實(shí)現(xiàn)將Parent的屬性和方法追加到Child中，從而實(shí)現(xiàn)繼承  //第一步：this.method是作為一個(gè)臨時(shí)的屬性，并且指向Parent所指向的對(duì)象，  //第二步：執(zhí)行this.method方法，即執(zhí)行Parent所指向的對(duì)象函數(shù)  //第三步：銷(xiāo)毀this.method屬性，即此時(shí)Child就已經(jīng)擁有了Parent的所有屬性和方法   this.method = Parent;  this.method(username);//最關(guān)鍵的一行  delete this.method;  this.password = password;  this.world = function(){   alert(this.password);  }}var parent = new Parent("zhangsan");var child = new Child("lisi","123456");parent.hello();child.hello();child.world();

function test(str){  alert(this.name + " " + str);}var object = new Object();object.name = "zhangsan";test.call(object,"langsin");//此時(shí)，第一個(gè)參數(shù)值object傳遞給了test類(lèi)(即方法)中出現(xiàn)的this，而第二個(gè)參數(shù)"langsin"則賦值給了test類(lèi)(即方法)的strfunction Parent(username){  this.username = username;  this.hello = function(){   alert(this.username);  }}function Child(username,password){  Parent.call(this,username);  this.password = password;  this.world = function(){   alert(this.password);  }}var parent = new Parent("zhangsan");var child = new Child("lisi","123456");parent.hello();child.hello();child.world();

function Parent(username){   this.username = username;   this.hello = function(){    alert(this.username);   } } function Child(username,password){   Parent.apply(this,new Array(username));   this.password = password;   this.world = function(){    alert(this.password);   } } var parent = new Parent("zhangsan"); var child = new Child("lisi","123456"); parent.hello(); child.hello(); child.world(); 

function Person(){ } Person.prototype.hello = "hello"; Person.prototype.sayHello = function(){   alert(this.hello); } function Child(){ } Child.prototype = new Person();//這行的作用是：將Parent中將所有通過(guò)prototype追加的屬性和方法都追加到Child，從而實(shí)現(xiàn)了繼承 Child.prototype.world = "world"; Child.prototype.sayWorld = function(){   alert(this.world); } var c = new Child(); c.sayHello(); c.sayWorld(); 

function Parent(hello){   this.hello = hello; } Parent.prototype.sayHello = function(){   alert(this.hello); } function Child(hello,world){   Parent.call(this,hello);//將父類(lèi)的屬性繼承過(guò)來(lái)   this.world = world;//新增一些屬性 } Child.prototype = new Parent();//將父類(lèi)的方法繼承過(guò)來(lái) Child.prototype.sayWorld = function(){//新增一些方法   alert(this.world); } var c = new Child("zhangsan","lisi"); c.sayHello(); c.sayWorld();