chrome.storage sorts object keys when it shouldn't?

[thdoan]

Steps to reproduce:

1. Open up any extension background page and enter this:
   
   
   chrome.storage.local.set({

     'obj': {

       'k1': 'one',

       'k2': 'two',

       'k10': 'ten'

     }

   });
   
   
2. Now play it back:
   
   
   chrome.storage.local.get('obj', function(items) {

     for (var i in items['obj']) {

       console.log(i);

     }

   });

Output:

k1
k10
k2

Expected output:

k1

k2

k10

The expected output is based on the assumption that chrome.storage sorts string object keys the same way Chrome does (i.e., unsorted). You can try this in the Chrome console to see the difference:

items = {
  'obj': {
    'k1': 'one',
    'k2': 'two',
    'k10': 'ten'
  }
};

// The code below outputs:
// k1
// k2
// k10
for (var i in items['obj']) {
  console.log(i);
}

So it appears chrome.storage is sorting the objects keys in lexicographic order. The ES6/ES2015 spec states that string keys should be kept in the order in which they're provided (source), so I hope chrome.storage will be updated to follow the latest spec.

[PhistucK]

Generally, if you want a sorted list, do not use an object, but an array.

Being sorted is an afterthought in objects.

☆PhistucK

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[thdoan]

Right, but I'm not commenting on developer best practice, I'm simply stating chrome.storage is not adhering to latest ES specs, which can be confusing to developers since V8 does not sort but the chrome.storage API does. It would help to be consistent; whether developers rely on object key order or not is auxiliary to the discussion ;-).