Random select array item without duplicates without removing items (JavaScript)

Question

I have seen many questions concerning randomly selecting array items without repeating. However, most of them are answered by using the splice method. But this removes items

Answer 1

If you want to go through an array in random order without modifying the original array:

1. Make a copy of the array with ary.slice() (this will copy the array, but not its values if they are objects).
2. Shuffle the copy.
3. Iterate through the copy.

var items = ["a", "b", "c", "d", "e", "f", "g"];

var copy = getShuffledCopy(items);
copy.forEach(function (el) {
    console.log(el);
});



function getShuffledCopy(ary){
    var copy = ary.slice();
    shuffle(copy);
    return copy;
}

function swap(ary, pos1, pos2) {
    var tmp = ary[pos1];
    ary[pos1] = ary[pos2];
    ary[pos2] = tmp;
}

function shuffle(ary){ 
    // Fisher-Yates shuffle
    for(var i = ary.length - 1; i >= 1; i -= 1) {
        swap(ary, Math.floor(Math.random() * i), i);
    }
}