4.1

var reverseArray = function(arr) {
    var arr2 = [];
    for (var i = arr.length - 1; i >= 0; i--)
        arr2.push(arr[i]);
    return arr2;
};
var reverseArrayInPlace = function(arr) {
    var arr2 = 0;
    for (var i = 0; i < arr.length / 2; i++) {
        arr2 = arr[i];
        arr[i] = arr[arr.length - i - 1];
        arr[arr.length - i - 1] = arr2;
    }
};

console.log(reverseArray(["A", "B", "C"]));
// → ["C", "B", "A"];
var arrayValue = [1, 2, 3, 4, 5];
reverseArrayInPlace(arrayValue);
console.log(arrayValue);
// → [5, 4, 3, 2, 1];