Are Javascript Object Properties assigned in order?

Question

Say I have an object which assigns properties based off the return value of a function:

var i = 0;

var f = function() { return ++i; }

var foo = {
                  


        

Answer 1

Standard ECMA-262 (5.1) - Section 11.1.5 - Object Initialiser

The production PropertyNameAndValueList : PropertyNameAndValueList , PropertyAssignment is evaluated as follows:

1. Let obj be the result of evaluating PropertyNameAndValueList.
2. Let propId be the result of evaluating PropertyAssignment.
...
5. Call the [[DefineOwnProperty]] internal method of obj with arguments propId.name, propId.descriptor, and false.
6. Return obj.

So yes, the order is enforced by the standard.