javascript object sort

<script>

function sortObj(list, key) {
    function compare(a, b) {
        a = a[key];
        b = b[key];
        var type = (typeof(a) === 'string' ||
                    typeof(b) === 'string') ? 'string' : 'number';
        var result;
        if (type === 'string') result = a.localeCompare(b);
        else result = a - b;
        return result;
    }
    return list.sort(compare);
}

var cars= [{brand: 'audi', speed: 240}, {brand: 'fiat', speed: 190}];
//var carsSortedByBrand = sortObj(cars, 'brand');
var carsSortedBySpeed = sortObj(cars, 'speed');

console.log(cars)

var mobile= {};
mobile[0]={brand: 'audi', speed: 240}
mobile[1]={brand: 'fiat', speed: 190}

var mobileBySpeed = sortObj(cars, 'speed');
console.log(mobileBySpeed)


</script>