Associative array loop order

Question

I have an associative array (object) in wich I store data loaded from a 3rd party.

// 3rdPartyData is also an associative array
for(var key in 3rdPartyData) {
  cookie[key] = 3rdPartyData[key];
}

My object gets stored into a cookie at the end and gets loaded form a cookie before (or created {} if no cookie exists).

Each page view the data from the 3rd party gets added or updated in my cookie array.

Question: If I wore to look the cookie, would the loop always get each key in the order they wore added to it or would the order be changed?

If so can anyone provide an idea on how to manage something like this?

The order of keys in an object is trivial but you could make an array of objects. — elclanrs, Jul 08 '13 at 08:54
JavaScript does not have associative arrays. You are probably talking about object keys and their order is not guaranteed. — Álvaro González, Jul 08 '13 at 08:56
@dystroy: I mean it doesn't really matter, because you have named keys right? — elclanrs, Jul 08 '13 at 08:57
So how do you suggest I go about this? I don't really wan to crate a loop in a loop. — transilvlad, Jul 08 '13 at 09:09

score 0 · Answer 1 · answered Jul 08 '13 at 09:02

0

The order of keys in for(var key in some_object) can be any, and certainly is not always sorted, but you can force the order to be the one you want:

for(var key in Object.keys(3rdPartyData).sort(keysSorter) {
    cookie[key] = 3rdPartyData[key];
}

keysSorter = function(a, b) {
    if (a === b) { // Should not actually be the case when sorting object keys
        return 0; 
    }
    // Compare a and b somehow and return 1 or -1 accordingly
    return a < b ? 1 : -1;
}

And to make sure Object.keys() will work:

Object.keys = Object.keys || function(o) {  
    var result = [];  
    for(var name in o) {  
        if (o.hasOwnProperty(name))  
            result.push(name);  
        }  
    return result;  
};

answered Jul 08 '13 at 09:02

mishik

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Note, that `Object.keys(3rdPartyData)` is not supported in EVERY browser. IE<9 doesn't have this. – Olegas Jul 08 '13 at 09:04
2

Yes, but it can be easily added... – mishik Jul 08 '13 at 09:06
@Olegas: You mean "is not supported in *every* browser" I presume. Firefox and Chrome support it. – Felix Kling Jul 08 '13 at 09:07
@FelixKling yes, thank you. – Olegas Jul 08 '13 at 09:08

Associative array loop order

1 Answers1