Sort Array by occurrence of its elements

Question

I'm looking for an elegant way of sorting an array by the occurrence of its elements.

For example, in:

['pear', 'apple', 'orange', 'apple', 'orange', 'apple']

the output should look like

['apple', 'orange', 'pear']

I have tried to loop through the array and save the occurrence in another temporary array, but this solution was quite bad.

Answer 1

It would require two loops.

    var arr = ['pear', 'apple', 'orange', 'apple', 'orange', 'apple'];
    //find the counts using reduce
    var cnts = arr.reduce( function (obj, val) {
        obj[val] = (obj[val] || 0) + 1;
        return obj;
    }, {} );
    //Use the keys of the object to get all the values of the array
    //and sort those keys by their counts
    var sorted = Object.keys(cnts).sort( function(a,b) {
        return cnts[b] - cnts[a];
    });
    console.log(sorted);