Question

Possible Duplicate:
Self-references in object literal declarations

var obj = {
    value: 10,
    value2: value + 2
};

How can I do the above? (Assuming it’s even possible)

I am using a lot of jQuery’s $.extend to add more properties that rely on the previous values being added; so that modifying a few values automatically correct the rest.

Answer 1

You can’t do it in declaration, but you could always make a function. The following will always return a value 2 greater than that stored in value:

var obj = {
    value: 10,
    getValue2: function(){ return this.value + 2; }
};

If you don’t want the value of value2 to change along with value, you could declare a placeholder variable and declare the object using that:

var placeholder = 10;

var obj = {
    value: placeholder,
    value2: placeholder + 2
};