How to iterate javascript object properties in the order they were written

Question

I identified a bug in my code which I hope to solve with minimal refactoring effort. This bug occurs in Chrome and Opera browsers. Problem:

var obj = {23:\"A         


        

Answer 1

I did not get your result when the object property identifiers were alphabetic strings. IE8, FF5, Chrome 12, and Opera 9.8 all kept the creation order, i.e.

Key: AA Value: 23 Key: BB Value: 12

It was when the identifiers were numbers that the results matched yours:-

IE8, FF5 --> Key: 23 Value: AA Key: 12 Value: BB

Opera, Chrome --> Key: 12 Value: BB Key: 23 Value: AA

Opera and Chrome are storing in reverse of creation order because 12 is less than 23, so if you use instead say:-

var obj = {2:"AA",12:"BB"};

then you get this result for all 4 browsers:-

Key: 2 Value: AA Key: 12 Value: BB

So it is the use of numbers as identifiers that causes the discrepancy. If identifiers are alphabetic then both creation and stored property orders are the same for the 4 browsers. This is despite ECMA rules that the stored order need not be related to creation order.

If the string identifiers are numeric e.g. '23' and '12', then Opera and Chrome treat them as numbers and again reverse the creation order, so that type are not permitted either. '23a' types are OK as are 'a23' type.

To answer your question, use non-numeric string identifiers and the behaviour will be the same across the 4 browsers (and possibly all browsers).