object vs. primitive

javascript oop object primitive
Zach Shallbetter picture Zach Shallbetter · Dec 27, 2011 · Viewed 30.8k times · Source

Recently had an interviewer ask to define the difference between objects and primitives. Seemed like an odd question considering that all languages begin with a primitive. How would you have answered this question?

I should also note that this interview was for a front-end development position so the language (I assume) he was referring to was JavaScript.

Answer

Mithun Sasidharan picture Mithun Sasidharan · Dec 27, 2011

A primitive is a data type that is composed of no other data types and can not be broken down any further. It is like the atoms in the programming scenario. I say atom because atom is a basic unit of matter and there is nothing that can be derived from it.

I mean, an int in C can not be broken down into smaller data type. An object, on the other hand can be thought of a molecule, consisting of more than one primitive type. For example, string comes as part of the C++ standard library; however, it is an object and it is composed of smaller data types internally and contains methods.

It is important to note that not all object-oriented languages are class based (eg. Javascript) You can not define a class in Javascript, so an object is quite different here. Even though everything in Javascript is an object (Ruby also), the Number object is really a wrapper for an internal primitive.

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