Object and primitive type equality

Question

I know that identical objects are not equal, i.e:

var obj = { name: \"Value\" };
var obj2 = { name: \"Value\" };

console.log(\"obj equals o         


        

Answer 1

First off, JavaScript objects aren't part of the DOM. The DOM (Document Object Model) are the HTML elements which make up your page. They cooperate together, but aren't directly linked.

Basically, yes, primitives are a special case. You can kind of think of it as if the value of a primitive is a constant (in a sense).

For example, take the example of the number 5. No matter how many times I declare 5, 5 will always equal 5. Thus, it isn't a stretch to say that {var a holding the value 5} is equivalent to {var b holding the value 5}. This concept is a little fuzzier with strings, but it still holds. A string that is "abc" is always the same as any other variable holding a string that is "abc".

This doesn't apply to objects either.

If you have two variables hold the same object, they are eqivalent.

var a = {};
var b = a;
console.log(a == b); // true
console.log(a === b); // true

However, if we create two objects that look similar:

var a = {};
var b = {};
console.log(a == b); // false
console.log(a === b); // false

This seems a bit weird at first, but think about the inner workings that are going on. Consider that when you pass an object in to a function, if you change that object, it is changed outside of the function to. It's passed by reference.

This means you can think of a pointer (a memory address) being stored in the variables. So, if you imagine that they have memory address in them (like 0x123456 and 0x654321), then it makes a little more sense (0x123456 and 0x654321 are different, so you wouldn't expend them to be equal). They are two separate things taking up their own area in the memory.

Make sense?