JavaScript: Can I define a property of an object using another property belonging to the same object using literal notation?

Question

Possible Duplicate:

• Self-references in object literals / initializers
• Javascript Object Literal referring to another property in itself from another property

var var1 = {};

var1.number = 20;
var1.numberplus3 = var1.number + 3;
console.log(var1.numberplus3);

var var2 = {
    number: 20,
    numberplus3: number + 3
};
console.log(var2);

In this example var1.numberplus3 evaluates to 23 but var2.numberplus3 evaluates to "undefined". Why is this?

(I am using the JS interpreter over at Codecademy: http://labs.codecademy.com/#:workspace)

Thanks!

Answer 1

you should write like:

var var2 = {
    number: 20,
    numberplus3: function() { return var2.number + 3; }
}

or:

var var2 = {
    number: 20
};
// at this point the var2 object is defined and accessible in the memory
var2.numberplus2 = var2.number+3;