Sort a Javascript Array by frequency and then filter repeats

Question

What is an elegant way to take a javascript array, order by the frequency of the values, and then filter for uniques?

So,

[\"apples\", \"oranges\", \"o

Answer 1

Basic strategy:

Create an object to use as a hash table to track the frequency of each item in the array to be sorted.

Create a new array containing the item, frequency pairs.

Sort this array on frequency in descending order.

Extract the items from that array.

Code:

function descendingUniqueSort(toBeSorted) {
    var hash = new Object();
    toBeSorted.forEach(function (element, index, array) { 
                           if (hash[element] == undefined) {
                               hash[element] = 1;
                           }
                           else {
                               hash[element] +=1;
                           }});
    var itemCounts = new Array();
    for (var key in hash) {
       var itemCount = new Object();
       itemCount.key = key;
       itemCount.count = hash[key];
       itemCounts.push(itemCount);
    }
    itemCounts.sort(function(a,b) { if(a.countb.count) return -1; else return 0;});

    return itemCounts.map(function(itemCount) { return itemCount.key; });
 }