9.2.1 prototype属性.html

javascript即用即差核心对象手册

<script>
  //定义函数，根据数字获取汉字周次
   function ChinseDay(numDay)
   {
      switch(numDay)
      {
         case 0:
             return "星期天";
             break;
         case 1:
             return "星期一";
             break;
         case 2:
             return "星期二";
             break;
         case 3:
             return "星期三";
             break;
         case 4:
             return "星期四";
             break;
         case 5:
             return "星期五";
             break;
         case 6:
             return "星期六";
      }
   }
   //将定义的函数添加到Date对象中
   Date.prototype.getChinseDay=ChinseDay;
   var objdate=new Date();
   //通过Date对象的实例调用新方法
   document.write("今天是"+objdate.getChinseDay(objdate.getDay()));
</script>