define method on built-in type in javascript

Question

Problem for example: In general null object means additional class which handle cases when object not found etc. In Ruby you can also define method for Nil class. And I want realise something similiar in js.

That's what gives me hope typeof(null) //=> object, but in same time null instanceof Object //=> false. So defining method for Object gives me nothing.

So the final question: is there any hacks to define method on built-in types?

I agree with you, sometimes programmers are too serious (or not enough?). "Don't extend buit-in classes", "Eval is evil"... Annoying quotes, often used as sledgehammer arguments, but also often recited without thinking. That said, I wonder if you could create your own Nil object. — user1636522
– user1636522, Commented Dec 8, 2013 at 10:18
@wared Overall, I wanted to hear some old legacy hacks like __proto__ or getters and setters. Now (when I understand futility of my question) typeof(null) //=> object seems like a joke of js developer. It's funny represent it like haskell data object = null | Object a — vlastachu
– vlastachu, Commented Dec 8, 2013 at 10:40
@wared well, I'd say that in this case, and in case of "eval is evil" there is a pretty sound, proven by many years, justification. — ZenMaster
– ZenMaster, Commented Dec 8, 2013 at 11:32

ZenMaster · Accepted Answer · 2013-12-08 09:21:04Z

1

Please don't.

That's really bad form and will lead to nasty, hard to find, bugs.

Or if you do - do it with greatest of cares.

Read here for more: http://perfectionkills.com/extending-built-in-native-objects-evil-or-not/

answered Dec 8, 2013 at 9:21

ZenMaster

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2 Comments

vlastachu Over a year ago

Everything is so serious about the js. I just make little web pages and not impose my approaches.

ZenMaster Over a year ago

Well, for us, those who are "so serious" about the JS, it's a matter of professionalism.

HIRA THAKUR · Accepted Answer · 2013-12-08 09:46:35Z

0

You can do that in javascript too.

I am not sure whether I understand your question.But here is my take on it.

alert(typeof(null));//gives you object.

MyObject=Object.create(null);

This means

MyObject doesn't inherit from anywhere
MyObject has no properties at all.

answered Dec 8, 2013 at 9:46

HIRA THAKUR

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5 Comments

vlastachu Over a year ago

May be this is right answer. For example var x = myset.findByName("name");/*return null*/ x.getWidth() /*return 0 or other default value*/. To formalise my question: you should execute null.SomeMethod().

ZenMaster Over a year ago

But it will be truthy.

HIRA THAKUR Over a year ago

Its good that you want to learn about this,but practically this wont be used much..

vlastachu Over a year ago

@Onaseriousnote It can be viewed from two sides. It would be great if you are going to write according to strict standards. At the same time, many people are unaware of the operator delete as not interested in the subtleties of language. Although yes maybe for nothing in language have introduced override built-in objects. And dynamic typing. And a prototype model.

HIRA THAKUR Over a year ago

by overriding you mean to manipulate already given functionality...?like for example to modify toString() at its core?

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