<script type="text/javascript">
	var life = {};	//关溜溜的生命对象
	for (life.age=1 ; life.age<=3; life.age++) {
		switch(life.age) {
			case 1:
				life.body = "卵细胞";	//增加body属性
				life.say = function() {alert(this.age + this.body)};	//新建say方法
				break;
			case 2:
				life.tail = "尾巴";	//增加tail属性
				life.gill = "腮";	//增加gill属性
				life.body = "蝌蚪";	
				life.say = function() {alert(this.age + this.body + "-" + this.tail +","+ this.gill)};
				break;
			case 3:
				delete life.tail;	//删除tail属性
				delete life.gill;	//删除gill属性
				life.legs = "四条腿";	//	增加legs属性
				life.lung = "肺";	//增加lung属性
				life.body = "青蛙";
				life.say = function() {alert(this.age + this.body +"-"+ this.legs +","+ this.lung)}
				break;
		};
		life.say();		//调用say方法，此方法逻辑每次都会动态改变
	};
</script>

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