# Trying to understand JavaScript from Ruby's view

**URL:** <https://www.ruby-forum.com/t/trying-to-understand-javascript-from-rubys-view/72624>\
**Category:** Ruby\
**Created:** [October 18, 2006, 10:39am UTC](https://www.ruby-forum.com/t/trying-to-understand-javascript-from-rubys-view/72624 "2006-10-18T10:39:26Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![ssk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/82dd89/32.png) [@ssk](https://www.ruby-forum.com/u/ssk)\
**Post date:** [October 18, 2006, 10:39am UTC](https://www.ruby-forum.com/t/trying-to-understand-javascript-from-rubys-view/72624/1 "2006-10-18T10:39:26Z")

</div>

Hi Rubyists,

I have a question which is not directly about ruby but about other  
language (but from ruby’s view).  
I may have to post to other newsgroups.  
So if you think this posting is inappropriate, forgive me.

I understand how ruby implements value types (Fixnum, TrueClass,  
FalseClass, NilClass) and reference types (other classes).  
To separate them, the last 2 bits (or 3?) of variables are used as  
flags (integer is 31-bit instead of 32-bit).  
And I think that’s a really genuis design.

I wanted to compare that design to JavaScript.  
In JavaScript, numbers(8 bytes), booleans, null, and undefined are  
immediate values and all others are references.  
I want to know how they are handled in memory (like variable size, bit  
flags, etc.) especially how differently they are implemented from  
ruby’s implementation.  
I couldn’t find a good document about it.  
Yesterday, I posted the question to comp.lang.javascript but nobody  
seems to care so far.  
So I’m begging some help to rubyists who also understand JavaScript  
well.

If possible, I also want to hear about python.  
I read some postings regarding this issue in comp.lang.python, it seems  
like everything in python is reference type unlike ruby.  
Is it true?

I’m nervous that somebody might throw me a stone for this off-topic  
posting.  
I hesitated a lot before posting.  
But I thought this was the best to get the answer.

Thanks.

Sam

---

<div class="post-metadata">

**Author:** ![ssk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/82dd89/32.png) [@ssk](https://www.ruby-forum.com/u/ssk)\
**Post date:** [October 18, 2006, 10:40am UTC](https://www.ruby-forum.com/t/trying-to-understand-javascript-from-rubys-view/72624/2 "2006-10-18T10:40:29Z")

</div>

> I wanted to compare that design to JavaScript.  
> In JavaScript, numbers(8 bytes), booleans, null, and undefined are  
> immediate values and all others are references.  
> I want to know how they are handled in memory (like variable size, bit  
> flags, etc.) especially how differently they are implemented from  
> ruby’s implementation.  
> I couldn’t find a good document about it.

It would be implementation specific. In Rhino, they are Classes (ref  
types), and in KJS they are structs. So, the rather unhelpful answer  
is, it depends. It’s not specified in the ECMA standard.

Martin