What is the correct Ordering of this Javascript Array?

Question

In Firefox the output is ordered Alphabetically (which is the order they are declared). In IE and Chrome they are numerical. All latest versions.

Which is correct?

<html>
<head></head>
<body>
<script type="text/javascript">
function makeArray()
{
    var array = [{5:'Five',4:'Four',1:'One',3:'Three',2:'Two'}];
    var msg = '';

    for (var val in array[0])
    {
        msg = msg + val;
    }   
    alert(msg);
}
</script>
<input type="button" onClick="makeArray();" value="Press Me" />
</body>
</html>

Back Story... In SpiraTeam (Our current bug tracking system) many of the lists (users, modules, etc) are ordered using a similar format to the above. This makes finding stuff very hard and annoying unless you use FireFox. My interest is purely academical, I only ask because I want to know which browser's correct.

There's actually only one item in the array - and object with 5 properties. So I think the correct way to phrase the question is "what is the correct ordering of properties in an object?" — selbie
– selbie, Commented Oct 3, 2011 at 20:25
You can find more info about order of iteration in a object here stackoverflow.com/questions/280713/… — Narendra Yadala
– Narendra Yadala, Commented Oct 3, 2011 at 20:25

Community · Accepted Answer · 2017-05-23 12:19:56Z

5

Actually you are asking: what is the order of properties within object literal when iterating using for loop? The array is irrelevant here.

And the answer is: it is unspecified. Most of the time it will be the same as you see in the code, but there is no guarantee.

This question has been asked hundreds of times:

edited May 23, 2017 at 12:19

CommunityBot

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answered Oct 3, 2011 at 20:22

Tomasz Nurkiewicz

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1 Comment

DaveShaw Over a year ago

Thanks, I just didn't know what to search for - I'm not a web developer :)

stevebot · Accepted Answer · 2011-10-03 20:21:18Z

1

Your issue seems to be that you are not iterating over an Array, but an Object...

ECMA doesn't seem to define in step 5 how to go about this... (alphabetically, numerically etc)

answered Oct 3, 2011 at 20:21

stevebot

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1 Comment

DaveShaw Over a year ago

It's not me who's doing it - that's just the code for the bug tracker I am stuck with.

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