JavaScript 面向对象编程

来源：互联网发布：淘宝分销骗局编辑：程序博客网时间：2024/05/22 20:25

1、模拟重载

在Java中重载是在一个类里面，方法名字相同，而参数不同。返回类型可以相同也可以不同。每个重载的方法（或者构造函数）都必须有一个独一无二的参数类型列表。由于JavaScript是弱类型，所以没有直接的机制去实现参数重载，但是我们可以通过传入的参数个数来进行模拟的重载。

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function Person(){
var args=arguments;
if(typeof args[0]==='object'&&args[0]){//判断参数是否是对象
if(args[0].name){
this.name=args[0].name;
}
if(args[0].age){
this.age=args[0].age;
}
}else{//参数不是对象
if(args[0]){
this.name=args[0];
}
if(args[1]){
this.age=args[1];
}
}
}
Person.prototype.toString=function(){
return 'name='+this.name+',age='+this.age;
};
var zou=new Person('zou',24);
alert(zou.toString());//name=zou,age=24
var miao=new Person({name:'miao',age:25})
alert(miao.toString());//name=miao,age=25

2、调用子类的方法

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function Person(name){this.anme=name;}
function Student(name,className){
this.className=className;
Person.call(this,name);//Student继承Person类
}
var zou=new Student('zou','class319');
zou;//Student{className:'class319',name:'zou'}
Person.prototype.init=function(){};
Student.prototype.init=function(){
//do sth
person.prototype.init.apply(this,arguments);
}

3、链式调用

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function ClassManager(){}
ClassManager.prototype.addClass=function(str){
alert('Class:'+str+' added');
return this;//this指向ClassManager的实例
};
var manager=new ClassManager();
manager.addClass('Math')
.addClass('English')
.addClass('Subject');
//Class:Math added
//Class:English added
//Class:Subject added

4、模拟抽象类

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function DetectorBase(){
throw new Error('Abstract class can not be invoked directly!');
}
DetectorBase.detect=function(){console.log('Detection starting...')};
DetectorBase.stop=function(){console.log('Detection stropped.');}
DetectorBase.init=function(){throw new Error('Error');}//想让子类型覆盖，但是又不想子类型直接调用，可以抛出异常
function LinkDetector(){}
LinkDetector.prototype=Object.create(DetectorBase.prototype);
LinkDetector.prototype.constructor=LinkDetector;

5、defineProperty()

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function Person(name){
Object.defineProperty(this,'name',{
value:name,
enumerable:true
});
}
Object.defineProperty(Person,'ARMS_NUM',{
value:2,
enumerable:true
});
// {writable: true, enumerable: true, configurable: false}
Object.seal(Person.prototype);
Object.seal(Person);
function Student(name,className){
this.className=className;
Person.call(this,name);
}
Student.prototype=Object.create(Person.prototype);
Student.prototype.constructor=Student;

6、模块化

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var moduleA
//prop和func不会被泄漏到全局作用域
moduleA=function(){
var prop=1;
function func(){}
return{
func:func,
prop:prop
}
}();//立即执行
var moduleB
moduleB=new function(){
var prop=1;
function func(){}
this.func=func,
this.prop=prop
};

7、实例

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//立即执行的函数表达式，把内部的函数、变量等包裹住，可以防止变量、函数声明或函数参数泄漏到外部
(function(global) {//global==this，浏览器就是window，nodejs就是Global
function DetectorBase(configs) { //基类
if (!this instanceof DetectorBase) {//防止外部不通过new而是直接调用函数
throw new Error('Do not invoke without new.');//直接调用抛出错误
}
this.configs = configs;
this.analyze();//解析数据
}
//抽象方法，应该被继承，直接调用抛出错误
DetectorBase.prototype.detect = function() {
throw new Error('Not implemented');
};
DetectorBase.prototype.analyze = function() {
console.log('analyze...');
this.data = "###data###";
};
//以下是两个实际的子类
function LinkDetector(links) {
DetectorBase.apply(this, arguments);
if (!this instanceof LinkDetector) {
throw new Error('Do not invoke without new.');
}
this.links = links;
}
function ContainerDetector(containers) {
DetectorBase.apply(this, arguments);
if (!this instanceof ContainerDetector) {
throw new Error('Do not invoke without new.');
}
this.containers = containers;
}
//实现原型链的继承
inherit(LinkDetector, DetectorBase);
inherit(ContainerDetector, DetectorBase);
// expand later
LinkDetector.prototype.detect = function() {
console.log('Loading data:' + this.data);
console.log('link detection started.');
console.log('Scaning links:' + this.links);
};
ContainerDetector.prototype.detect = function() {
console.log('Loading data:' + this.data);
console.log('link detection started.');
console.log('Scaning containers:' + this.containers);
};
// prevent from being altered
//{writable: false, enumerable: true, configurable: false}
Object.freeze(DetectorBase);
Object.freeze(DetectorBase.prototype);
Object.freeze(LinkDetector);
Object.freeze(LinkDetector.prototype);
Object.freeze(ContainerDetector);
Object.freeze(ContainerDetector.prototype);
// export to global object
Object.defineProperties(global, {
LinkDetector: { value: LinkDetector },
ContainerDetector: { value: ContainerDetector },
DetectorBase: { value: DetectorBase }
});
//寄生组合式继承
function inherit(subClass, superClass) {
subClass.prototype = Object.create(superClass.prototype);
subClass.prototype.constructor = subClass;
}
}(this));
var zm = new ContainerDetector('#span #div #input');
zm.detect();
var zz = new LinkDetector('http://blog.csdn.net/qq_27626333');
zz.detect();

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