js中的extend拷貝

var toString=Object.prototype.toString;
var extend = function( src) {
	var dest;
    if ( toString.call(src) == "[object Array]") {
        dest = [];
        for (var i = 0; i < src.length; i++) {
            dest[i] = extend(src[i])
        }
    }else if(toString.call(src) == "[object Object]"){
    	dest={};
    	for(var key in src){
    		dest[key]=extend( src[key] );
    	}
    }else{
    	dest=src;
    }

    return dest;
}
var b={
	a:[1,2],
	b:{
		c:function(){ console.log(1) }
	}
}
var a=extend(b);
a.a[1]=999;
a.b.c=function(){ console.log(222) };
console.log(a)
console.log(b)
a.b.c();
b.b.c();
//js中的數據結構拷貝可以直接用extend