let Dnevnik = {math: 65, philo: 85, physics: 60};
Math.max.apply(Math, Courses.map(function(o) { return o; }))
const values = Object.values(obj);
const min = Math.min(...values);
const max = Math.max(...values);
const [ min, max ] = Object
.values(obj)
.reduce(([ min, max ], n) => [
n < min ? n : min,
n > max ? n : max,
], [ Infinity, -Infinity ]);
let min = Infinity;
let max = -Infinity;
for (const k in obj) {
if (obj.hasOwnProperty(k)) {
const v = obj[k];
(min > v) && (min = v);
(max < v) && (max = v);
}
}