Question

Possible Duplicate:
JavaScript arrays braces vs brackets

I have a simple question that I can’t find an answer to with Google.
What is the difference between

var foo = { };

and

var bar = [ ];

An example would help.

Answer 1

foo = {} is not an array, but an object (created using object literals, {}).

bar = [] is an array, which inherit various methods from the Array constructor. An array also has various properties, such as .length.

EDIT (regarding comment):
The a property of an object can be accessed through foo.a or foo["a"].
Looping through the properties of the object should be done using a for( .. in .. ) loop.

var foo = {"a":true, "b":false};
for(var prop_name in foo){
    alert(prop_name + " - " + foo[prop_name]);
}

This code will show two alert messages:

a - true
b - false