Sorting Javascript associative array values in descending order

Question

I have the following method that gets the word frequency based on some input text:

function getWordFrequency(lowerCaseArray) {
    var wordFrequency = {};
    $.each(lowerCaseArray, function(ix, word) {
        // skip empty results
        if (!word.length) {
        return;
        }
        // add word to wordFrequency
        if (!wordFrequency[word]) {
        wordFrequency[word] = 0;
        } 
        wordFrequency[word]++;
    });
    return wordFrequency;
}

However, I would like to return the frequency of words on a descending order, i.e.

cats => 20
dogs => 19
frog => 17
humans => 10

Currently, my algorithm returns in the order in which the input words appear.

You can't sort objects. You can create an array of objects and sort it by using Array.prototype.sort method. — Ram
– Ram, Commented Nov 25, 2015 at 19:23
Another way to say it: there is no guarantee of the order of keys in an object — Ruan Mendes
– Ruan Mendes, Commented Nov 25, 2015 at 19:26
Object.keys(words).map(key => ( {key: key, count: words[key]} )).sort((a, b) => a.count - b.count); — Microfed
– Microfed, Commented Nov 25, 2015 at 19:30

Ruan Mendes · Accepted Answer · 2015-11-25 19:33:30Z

2

You have to return an array of objects if you want ordering. Properties of an object do not have a guaranteed order.

var obj = getWordFrequency(words);
var array = Object.keys(obj).map(function(key){
     return {word: key, count: obj[key]};
});
array.sort(function (a,b){ return b.count - a.count});

Typed from my phone, untested, order of a and b may need to be reversed

answered Nov 25, 2015 at 19:33

Ruan Mendes

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