一、创建对象的几种方式
1、工厂模式:缺点是不知道对象类型
function createPerson(age) {
var o = new Object();
o.age = age
o.sayAge = function() {
alert(this.age);
}
return o;
}
var p1 = createPerson(11);
var p1 = createPerson(12);
2、构造函数模式:缺点就是每一次new Person的时候都是创建一个Function对象实例(sayAge)
function Person(age) {
this.age = age;
this.sayAge = function() {
alert(this.age);
}
}
var p1 = new Person(11);
var p2 = new Person(12);
3、原型模式:缺点数据共享的问题
hasOwnProperty可以检测属性是实例属性还是原型中的属性;
in:对象能够访问属性的时候返回true;
function Person() {
}
Person.prototype={
constructor:Person,
name:"gt",
friends:['a','b'],
sayName:functon(){
alert(this.name);
}
};
var p1 = new Person();
var p2 = new Person();
p1.friends.push('c');
这样p1和p2都有朋友c这就是他们的问题所在
4、组合使用构造函数模式和原型模式
目前使用的最为广泛的一种模式
function Person(age) {
this.age=age;
}
Person.prototype = {
constructor:Person,
sayAge:function(){
alert(this.age);
}
}
var p1 = new Person(11);
var p2 = new Person(12);
5、动态原型模式
function Person(age) {
this.age=age;
if(typeof this.sayName != "function") {
Person.portotype.sayName = function() {
alert(this.name)
}
}
}
var p1 = new Person(11);
6、寄生构造函数模式
function SpecialArray() {
var values = new Array();
values.push.apply(values,arguments);
values.toPipedString = function() {
return this.join('|');
}
return values;
}
var colors = new SpecialArray('a','b');
7、稳妥构造函数模式:没有公共属性,而且其方法也没引用this的对象
function Person(age){
var o = new Object();
o.sayAge = function() {
alert(name);
}
return o;
}
var p1 = new Person(11);]
p1.sayAge();
只能通过sayAge方式来访问name,多用于比较安全的环境中
二、继承(主要通过原型链来实现)
1、原型链
function SuperType(){
this.property = true;
}
SuperType.propotype.getSuperValue = function(){
return this.property;
};
function SubType(){
this.subProperty=false;
}
SubType.prototype = new SuperType();
SubType.propotype.getSubTypeValue = function(){
return this.subProperty;
}
var instance = new SubType();
alert(instance.getSuperType());
2、借用构造函数
function SuperType(name){
this.name = name;
}
function SubType(){
SuperType.call(this,"nnnn");
this.age=20;
}
var instance = new SubType();
3、组合继承
function SuperType(name){
this.name= name;
this.colors = [1,2,3]
}
SuperType.propotype.sayName= function(){
alert(this.name);
};
function SubType(name,age){
SuperType.call(this,name);
this.age=age;
}
SubType.prototype = new SuperType();
SubType.prototype.constructor = SubType;
SubType.propotype.sayAge= function(){
alert(this.age);
}
var instance = new SubType('aaaa',20);
instance.colors.push(4);
4、原型式继承
function object(0) {
function F(){}
F.prototype=o;
return new F();
}
var person = {
name='1111';
friends=[1,3];
}
var p1 = object(person);
var p2 = object(person);
friends会被共享
//用Object.create方法实现
var p1 = Object.create(person);
var p2 = Object.create(person);
5、寄生式继承
function object(0) {
function F(){}
F.prototype=o;
return new F();
}
function createAnother(original) {
var clone = object(original);
clone.sayHi = function() {
alert('hi');
}
}
var person = {
name='1111';
friends=[1,3];
}
var p1 = createAnother(person);
p1.sayHi();
6、寄生组合式继承
function object(0) {
function F(){}
F.prototype=o;
return new F();
}
function inheritPrototype(subType,SuperType) {
var prototype=object(super.prototype);
prototype.constructor = subType;
subType.prototype=prototype;
}
function SuperType(name){
this.name = name;
this.colors = [1,2,3,4];
}
SuperType.prototype.sayName = function(){
alert(this.name);
}
function SubType(name,age) {
SuperType.call(this,name);
this.age = age
}
inheritPrototype(SubType,SuperType);
SubType.prototype.sayAge = function(){
alert(this.age);
}