JSFiddle - React, Tailwind, and code Playground

HTML

<span id="result"></span>

JavaScript

var cities = {
     "Токио — Иокогама" : 37555,
     "Берлин" : 1347,
     "Барселона" : 4656,
     "Белу-Оризонти" : 4486,
     "Сурабая" : 5057
}

function sort(array, num){
    var arTmp = [];
    var arResult = [];

    for(key in array) {
        arTmp.push(array[key]);
    }

    for (var i = arTmp.length - 1; i > 0; i--) {
        for (var j = 0; j < i; j++) {
            if (arTmp[j] < arTmp[j+1]) {
                var tmp = arTmp[j+1];
                arTmp[j+1] = arTmp[j];
                arTmp[j] = tmp;
            }
        }
    }

    for (var k = 0; k < num; k++) {
        arResult.push(arTmp[k]);
    }

    return arResult;
}
document.getElementById("result").innerHTML = sort(cities, 3) ;