js 封装类库

刚刚学了点js ,终于学会自己封装 类库了，好开森。贴上样式代码；

<script>
var BaseCalculator = (function(myself){

	/*
		construct funion 
	*/
	myself = function(){
		this.tax= 6;	
	};
	
	myself.prototype = {
		add:function(x,y){return x+y;},
		subtract:function(x,y){return x-y;}
	};	

	return myself;
}(BaseCalculator || function(){}));

//subclass Calculator 
var Calculator=(function(myself){
	
	//constructor	
	myself = function(){
		this.decimalDigits= 53;
	};

	//继承 BaseCalculator 
	myself.prototype= BaseCalculator.prototype;

	
	//重写父类方法
	var old_add = myself.prototype.add;
        BaseCalculator.prototype.old_add = old_add;
	myself.prototype.add = function(x,y){
		return x+y+100;
	};

	return myself;
	
}(Calculator || function(){}));


	var C = new Calculator();
	console.log("decimalDigits:"+C.decimalDigits);
	console.log("Calculator.add:"+C.add(343,42));
        var BC = new BaseCalculator();
	console.log("Base.add:"+BC.old_add(343,42));

</script>
结果：
decimalDigits:53 
Calculator.add:485 
old_add:385
Base.add:385