sorting data by object keys does not work when some of the keys are numeric [duplicate]

Question

I have object contain data like this

const testData = {
        "11": {
            "data": {
                "firstName": "firstName",
                "lastName": "lastName"
            }
        },
        "12": {
            "data": {
                "firstName": "firstName",
                "lastName": "lastName"
            }
        },
        "00": {
            "data": {
                "firstName": "firstName",
                "lastName": "lastName"
            }
        },
        "01": {
            "data": {
                "firstName": "firstName",
                "lastName": "lastName"
            }
        },
        "final": {
            "data": {
                "firstName": "firstName",
                "lastName": "lastName"
            }
        }
    }

i want to sort this data by object keys like 00, 01, 11, 12, final

i have tried like this but i can not achieve what i want.Any idea would be appreciate?

sorted = Object.keys(testData).sort().reduce((acc, key) => ({
  ...acc, [key]: testData[key]
  }), {})

console.log(sorted)

values who could be indices of arrays are sorted first, then by insertation order. double zero is not an index, as well as values with leading zeros. — Nina Scholz
– Nina Scholz, Commented Jul 1, 2019 at 14:26
JavaScript does not guarantee order of property keys. Not even in ES6. — VLAZ
– VLAZ, Commented Jul 1, 2019 at 14:38

Madara's Ghost · Accepted Answer · 2019-07-01 14:43:49Z

7

You cannot. The defined iteration order for JavaScript object keys is as follows:

Numeric keys, in ascending numeric order. (this includes strings such as "11", but not "01"), THEN...
String keys which are not numeric, in order of insertion. THEN...
Symbol keys, in order of their insertion.

As you can see, regardless of insertion order, numeric keys will always appear first in the iteration order, and always in their numeric order.

In your example, "11" and "12" will always end up first, regardless of what you do.

In general, relying on order with objects (which are essentially unordered dictionaries you access via key), is ill-advised. If order matters, you should be using an array. Alternatively, you can use a Map.

edited Jul 1, 2019 at 14:43

answered Jul 1, 2019 at 14:29

Madara's Ghost

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5 Comments

U rock Over a year ago

what if i add 0 infront of "11" like this "011". this will sort as we want, after sorting we need to remove first 0 in all keys.

Madara's Ghost Over a year ago

The moment you have, in your object, the key "11" and the key "01", "11" will always come first no matter what. If you add a padding 0, and then remove it before you put it in the object, you will accomplish nothing. Seriously though, use a Map, or an array.

U rock Over a year ago

can you please provide demo for using map in efficient way.

U rock Over a year ago

if i make "0", "1", "12", "14" something like this, can i expect guarantee order in all browsers

U rock Over a year ago

i have updated my post by adding special character before all keys.

Julliano Osorio · Accepted Answer · 2019-07-01 14:33:06Z

-2

Try something like this:

sorted = Object.keys(testData).sort((a,b) => {
    if (a < b) return -1;
    if (a > b) return 1;
    return 0;
});

console.log(sorted)

answered Jul 1, 2019 at 14:33

Julliano Osorio

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1 Comment

U rock Over a year ago

we can get above result with this Object.keys(testData).sort() that is not helpful and i should rotate whole data

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