I'm trying to copy Object class and then modify prototype of the new copied class. However, changes to new class prototype gets reflected to original Object class. Example:
var MyClass = Object;
MyClass.prototype.doSomething = function() {...};
Object.prototype.doSomething(); //it gets reflected to original object
Is there some way to copy a class without that annoying reflection (I know that sometimes it is a good thing, but right now, I just need to get rid of it)?
I would just use prototypical inheritance instead of worrying about "cloning" in this case. There are several JS libraries that can help with that.
Yes, you should create a new Object and use it for your prototype:
function MyClass(){}
MyClass.prototype = new Object;
MyClass.prototype.doSomething = function() { ... };
In modern engines you should use Object.create for this:
function MyClass(){}
MyClass.prototype = Object.create(Object.prototype);
MyClass.prototype.doSomething = function() { ... };
Actually, there is no way to copy a function reliably in Javascript. Provided that Object is another function you can do the following trick. Let's first rename it to Base not to shadow build-in Object function.
function MyClass(){
Base.apply(this, arguments); //call Base on a newly created object.
//the rest of configuration goes here.
};
MyClass.prototype = Object.create(Base.prototype); //"copy" Base.prototype. Notice Object is built-in function.
MyClass.prototype.constructor = MyClass; //We want instanceof to work...
MyClass.prototype.doSomething = function(){}; //Add new method.
Base.prototype.doSomething !== MyClass.prototype.doSomething; //true
