Question

The object

var obj = {
   uniquestring1:
   {
       obj1: 'content',
       obj2: 'content'
   },
   uniquestring2:
   {
       obj1: 'content'
   }
}

So i need to sort the object by number of the elements contained by the first parent element. The use of .sort function is not a sollution for me because i need to maintain the index assosiaction which array’s dont keep.

The result should be:

var obj = {
   uniquestring2:
   {
       obj1: 'content'
   },
   uniquestring1:
   {
       obj1: 'content',
       obj2: 'content'
   }
}

Answer 1

Javscript objects don’t have a sort order so they can’t be sorted. To sort, you must have an array somewhere and I see no array in your code.

Object keys have no defined order.

• If you only need ordered access, use an array.
• If you only need keyed access, use an object.
• If you need access by both, you can use a parallel array, but this is a pain unless the data is not changing.

You could do a one-time creation of a parallel array that contained key references in sorted order like this:

var obj = {
   uniquestring1:
   {
       obj1: 'content',
       obj2: 'content'
   },
   uniquestring2:
   {
       obj1: 'content'
   }
}

var objOrder = [];   // sorted arrays that contains first level keys into obj
var num;
for (var i in obj) {
    objOrder.push(i);  // get all keys into the array
    num = 0;
    for (var j in obj[i]) {
        ++num;         // count items in each key object
    }
    obj[i].keyCnt = num;   // save this for later sorting purposes
}
// now sort the parallel array by keyCnt
objOrder.sort(function(a, b) {
    return(obj[a].keyCnt - obj[b].keyCnt);
});

Then, to traverse the keys in sorted order, you would do it like this:

for (var i = 0; i < sortedOrder.length; i++ ) {
    var item = obj[sortedOrder[i]];
    // do something with item here
}