1. 組合繼承：又叫偽經(jīng)典繼承，是指將原型鏈和借用構(gòu)造函數(shù)技術(shù)組合在一塊的一種繼承方式。

下面來(lái)看一個(gè)例子：

function SuperType(name) {  this.name = name;  this.colors = ["red", "blue", "green"]; } SuperType.prototype.sayName = function() {  alert(this.name); } function SubType(name, age) {  SuperType.call(this, name);  this.age = age; }  //繼承方法 SubType.prototype = new SuperType(); SubType.prototype.sayAge = function() {  alert(this.age); }  var instance1 = new SubType("Nicholas", 29); instance1.colors.push("black"); alert(instance1.colors); //red,blue,green,black instance1.sayName(); //Nicholas instance1.sayAge(); //29  var instance2 = new SubType("Greg", 27); alert(instance2.colors); //red,blue,green instance2.sayName(); //Greg instance2.sayAge(); //27

組合繼承避免了原型鏈和借用構(gòu)造函數(shù)的缺陷，融合它們的優(yōu)點(diǎn)。

2. 原型式繼承

可以在不必預(yù)先定義構(gòu)造函數(shù)的情況下實(shí)現(xiàn)繼承，其本質(zhì)是執(zhí)行對(duì)給定對(duì)象的淺復(fù)制。而復(fù)制得到的副本還可以得到進(jìn)一步的改造。

function object(o) {  function F(){};  F.prototype = o;  return new F; }  var person = {  name: "Nicholas",  friends: ["Shelby", "Court", "Van"] };  var antherPerson = object(person); antherPerson.name = "Greg"; antherPerson.friends.push("Rob");  var antherPerson = object(person); antherPerson.name = "Linda"; antherPerson.friends.push("Barbie");  alert(person.friends); //Shelby,Court,Van,Rob,Barbie

3. 寄生式繼承

與原型式繼承非常相似，也是基于某個(gè)對(duì)象或某些信息創(chuàng)建一個(gè)對(duì)象，然后增強(qiáng)對(duì)象，最后返回對(duì)象。為了解決組合繼承模式由于多次調(diào)用超類型構(gòu)造函數(shù)而導(dǎo)致的低效率問(wèn)題，可以將這個(gè)模式與組合繼承一起使用。

function object(o) {  function F(){};  F.prototype = o;  return new F; } function createAnother(original) {  var clone = object(original);  clone.sayHi = function() {   alert("Hi");  };  return clone; }  var person = {  name: "Nicholas",  friends: ["Shelby", "Court", "Van"] };  var anotherPerson = createAnother(person); anotherPerson.sayHi();

4. 寄生組合式繼承

集寄生式繼承和組合繼承的優(yōu)點(diǎn)與一身，是實(shí)現(xiàn)基本類型繼承的最有效方式。

//繼承原型 function extend(subType, superType) {  function F(){};  F.prototype = superType.prototype;   var prototype = new F;  prototype.constructor = subType;  subType.prototype = prototype; }  //超類方法 function SuperType(name) {  this.name = name;  this.colors = ["red", "blue", "green"]; } SuperType.prototype.sayName = function() {  return this.name; }  //子類方法 function SubType(name, age) {  SuperType.call(this, name);  this.age = age; }  //繼承超類的原型 extend(SubType, SuperType);  //子類方法 SubType.prototype.sayAge = function() {  return this.age; }  var instance1 = new SubType("Shelby"); var instance2 = new SubType("Court", 28);  instance1.colors.push('black');  alert(instance1.colors); //red,blue,green,black alert(instance2.colors); //red,blue,green  alert(instance1 instanceof SubType); //true alert(instance1 instanceof SuperType); //true