Loop through json object and sort in order

Question

Currently I have a small piece of code which loops through a json object:

for (var key in json_object) {
    if (json_object.hasOwnProperty(key)) {
        var value       = key; //e.g. 50_100, 1000_2000, 20_50 etc
    }
}

I'm going to be outputting these values into a list later on. But the problem is that these values aren't in any order right now.

I'd like to be able to have these values sorted out in order. So my question is, is this possible and if so how?

Thanks!

Object keys don't have an order. If defined at compile time, order of keys is retained, else sorted by alphabetical order of keyname — gurvinder372, Mar 16 '16 at 13:48
You can make array of these key values and than sort it. As #gurvinder372 said - no sort for keys in object — S. Nadezhnyy, Mar 16 '16 at 13:50
My purpose is to be able to output them in an ordered list later on, so is there any alternative or other ways to achieve what I need? — user2028856, Mar 16 '16 at 13:53
@S.Nadezhnyy do you mean I save these values into an array and then sort that array? — user2028856, Mar 16 '16 at 13:53
@user2028856: You could serve an array (list) in the JSON that has the right order up front. — Bergi, Mar 16 '16 at 13:54

score 1 · Accepted Answer · answered Mar 16 '16 at 14:03

1

In javascript, object properties are not guaranteed a specific order, so if you want to maintain order, you would likely need to write the object properties into an array of objects.

That could look like this:

var object_array = [];
// map properties into array of objects
for (var key in json_object) {
    if (json_object.hasOwnProperty(key)) {
        object_array.push({
            'key': key;
            'value': value;
        });   
    }
}
// sort array of objects
object_array.sort(function(a,b) {
    // note that you might need to change the sort comparison function to meet your needs
    return (a.value > b.value);
}

answered Mar 16 '16 at 14:03

Mike Brant

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I tried this but it doesn't seem to perform any sorting for strings such as this "100_500" , "800_1000", "2000_3000" etc – user2028856 Mar 16 '16 at 14:40
@user2028856 That is why I indicated that you might need to change the sort comparison to do something applicable to the values you are sorting by. In the case of your strings, how would you propose to perform the sort? – Mike Brant Mar 16 '16 at 16:45
Your comparison function is invalid, see [Sorting in JavaScript: Shouldn't returning a boolean be enough for a comparison function?](http://stackoverflow.com/q/24080785/1048572) – Bergi Mar 16 '16 at 20:31

Asaf David · Answer 2 · 2016-03-17T08:05:01.657

0

After reading all solutions, I realized my solution was wrong. Object.keys is good for getting an array of keys only, so Mike Brant's solution is correct, although a little fix is needed since value is not a variable there. Finally here's a fixed solution based on his solution + the requested sorting from the comments:

var arr = [];

for (var key in json_object) {
    if (json_object.hasOwnProperty(key)) {
        arr.push({
            'key': key;
            'value': json_object[key];
        });   
    }
}

// this will sort by the first part of the string
arr.sort(function(a, b) {
  return a.key.split('_')[0] - b.key.split('_')[0];  
}

Hope this helps... :-)

edited Mar 17 '16 at 08:05

answered Mar 16 '16 at 13:53

Asaf David

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1

What is `value`? Probably not an array index. – Bergi Mar 16 '16 at 13:55
Can you please tell me what should I use for 'value'? – user2028856 Mar 16 '16 at 13:57
1

You can directly use `Object.keys(obj).sort(function(){})` – Rajesh Mar 16 '16 at 14:02
@user2028856 Fixed and also added another option following Rajesh's comment – Asaf David Mar 16 '16 at 14:31
Does this method provide sorting for strings like this: "100_500" , "800_1000", "2000_3000" etc? – user2028856 Mar 16 '16 at 14:40
It does sort, but probably not as you want it. If it compares two strings it will sort them as strings and not as number, you need to modify your values. How do you need them sorted exactly? – Asaf David Mar 16 '16 at 14:43
I'd like them sorted like this: "0_20", "20_50", "50_100", "100_300", "300_500", "500_1000", "1000_2000", "2000_3000", "3000_4000" – user2028856 Mar 16 '16 at 14:45
Right now they're like this: "100_300", "500_1000", "300_500", "1000_2000", "50_100", "20_50", "2000_3000", "3000_4000", "0_20" – user2028856 Mar 16 '16 at 14:45
That filter makes no sense, `Object.keys` already returns only own properties. – Bergi Mar 16 '16 at 20:30
Following all your comments, i've completely changed my answer + added the requested sorting. If you need to sort by the second part as well just let me know – Asaf David Mar 17 '16 at 08:06

Loop through json object and sort in order

2 Answers2