Sorting an array order by frequency of occurence in javascript

gistfile1.txt

/**
 *  Sorting an array order by frequency of occurence in javascript
 *  @param {array} array An array to sort
 *  @returns {array} array of item order by frequency
 **/
function sortByFrequency(array) {
    var frequency = {};
    var sortAble = [];
    var newArr = [];

    array.forEach(function(value) { 
        if ( value in frequency )
            frequency[value] = frequency[value] + 1;
        else
            frequency[value] = 1;
    });
    

    for(var key in frequency){
        sortAble.push([key, frequency[key]])
    }

    sortAble.sort(function(a, b){
        return b[1] - a[1]
    })

    
    sortAble.forEach(function(obj){
        for(var i=0; i < obj[1]; i++){
            newArr.push(obj[0]);
        }
    })
    return newArr;
    
}

gistfile2.txt

Example Suppose you have an array [2, 2, 1, 4, 2,5, 4,4,4, 5]

sortByFrequency([2, 2, 1, 4, 2,5, 4,4,4, 5])

Answer : [ '4', '4', '4', '4', '2', '2', '2', '5', '5', '1' ]

function SortElemByFrequencyObj(arr) {
const frequency = arr.reduce((obj, curr) => {
obj[curr] = (obj[curr] || 0) + 1;
return obj;
}, {});
return Object.entries(frequency).sort((a, b) => b[1] - a[1]).flatMap(item => Array(item[1]).fill(item[0]))
}

you can make this code compact by using lodash _.count method

import _ from 'lodash';
function SortElemByFrequencyObj(arr) {
const frequency = _.count(arr);
return Object.entries(frequency).sort((a, b) => b[1] - a[1]).flatMap(item => Array(item[1]).fill(item[0]));
}