[EmperioAf]

var check = {
    cn_el: ''
};
function hardWork(n /* string */) {
    check.cn_el = '';
    for (var el of n) {
        check.cn_el += el;
    }
    return check.cn_el
}

console.log(hardWork('234')); // '234'
console.log(check) // {cn_el: '234'}
console.log(hardWork('345')); // '345'
console.log(check) // {cn_el: '345'}
console.log(hardWork('456')); // '456'
console.log(check) // {cn_el: '456'}