javascript基于prototype实现类似OOP继承的方法

function Vegetable(){  this.taste='delicious';  var a = 'I/'m Vegetable/'a!'  this.fun1 = function(){    alert('Vegetable fun1 doing...');  }  this.fun3 = function(){    alert(a);  }}function Celery(){  var a = 'I/'m Celery/' a';  this.color = 'green';  this.taste = 'bad';  this.fun1a = function(){    alert('Celeryfun1 doing...');  }  this.fun2 = function(){    alert('Celery fun2 doing...');  }  this.fun4 = function(){    alert(a);  }}Celery.prototype = new Vegetable();var stick = new Celery();var polymorphed = stick.taste;//alert(polymorphed);//alert(stick.color);//stick.fun1();//stick.fun2();//stick.fun3();stick.fun4();