1. var proto = {
hoge: 1
};
var func = function() {};
func.prototype = proto;
var obj = new func();
alert( obj.hoge ); // 1
obj.hoge = 2;
alert( obj.hoge ); // 2
proto.hoge = 3;
alert( obj.hoge ); // 2
delete obj.hoge;
alert( obj.hoge ); // 3
delete proto.hoge;
alert( obj.hoge ); // undefined