JavaScript面向对象特性实践一

JavaScript面向对象特性实践一

javaScript 在构造类的时候有好几种方法，每种方法特点是不一样的。

1.构造/原型法

 

    var  BankCard=function(cardId,cardPassword)...{
         this.cardId=cardId;  //银行卡NO
         this.cardPassword=cardPassword;// 银行卡密码
         this.balance=100; //银行卡余额
}
    BankCard.prototype=...{
          queryBalance:function()...{
            return this.balance;
                        },
            setBalance:function(value)...{
             this.balance=this.balance+value;
                         },
           setPassword:function(password)...{
              this.cardPassword=password;
                         }
   }

 function   invoke(fun,value)...{
       fun.setBalance(value);
       balance=fun.queryBalance();
       alert(balance);
    }
//实例化一个银行卡对象
     var  objBankCard=new BankCard('admin','admin');
//传递对象引用，调用对象成员方法
      invoke(objBankCard,200);


//-->

 

2.工厂方式 

 

function BankCard(cardId,cardPassword,balance)...{
      var objBankCard=new Object();
      objBankCard.cardId=cardId;
      objBankCard.cardPassword=cardPassword;
      objBankCard.balance=balance;
      objBankCard.queryBalance=function()...{
          return this.balance;
      };
      objBankCard.setBalance=function(value)...{
          this.balance=this.balance+value;
      };
      objBankCard.setPassword=function(password)...{
          this.cardPassword=password;
      };


      return objBankCard;
}
     var obj=new BankCard("admin","admin",100);
     alert(obj.queryBalance());

3.构造函数方式

 

function BankCard(cardId,cardPassword,balance)...{
    
      this.cardId=cardId;
      this.cardPassword=cardPassword;
      this.balance=balance;
      this.queryBalance=function()...{
          return this.balance;
      };
      this.setBalance=function(value)...{
          this.balance=this.balance+value;
      };
      this.setPassword=function(password)...{
          this.cardPassword=password;
      };

}
     var obj=new BankCard("admin","admin",100);
     alert(obj.queryBalance());

 

4.原型方式

 

//原型方式
   function BankCard()...{

   }
   BankCard.prototype.carId="admin";
   BankCard.prototype.cardPassword="admin";
   BankCard.prototype.balance=100;
   BankCard.prototype.queryBalance = function()...{
               return this.balance;
                        };
        
    BankCard.prototype.setBalance = function(value)...{
          this.balance=this.balance+value;
      };
    BankCard.prototype.setPassword = function(password)...{
          this.cardPassword=password;
      };
     var obj=new BankCard();
     alert(obj.queryBalance());

 

  在日常的工作当中，推荐大家是由"构造/原型"法或"原型"法。