function print(arr, callback) {
    for (var i = 0; i < arr.length; i++) {
        callback(arr[i], i);
    }
}

function printElement(el) {
    console.log(el);
}

function printIndexAndElement(el, index) {
    console.log(index + " => " + el);
}

function printIndexAndIncrementElement(el, index) {
    console.log(index + " => " + (el + 2));
}

var numbers = [3, 5, 1];
print(numbers, printElement);
print(numbers, printIndexAndElement);
print(numbers, printIndexAndIncrementElement);