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How to get a number of random elements from an array?

I am working on ‘how to access elements randomly from an array in javascript’. I found many links regarding this. Like: Get random item from JavaScript array

var item = items[Math.floor(Math.random()*items.length)];

But in this, we can choose only one item from the array. If we want more than one elements then how can we achieve this? How can we get more than one element from an array?

Answer

Try this non-destructive (and fast) function:

function getRandom(arr, n) {
    var result = new Array(n),
        len = arr.length,
        taken = new Array(len);
    if (n > len)
        throw new RangeError("getRandom: more elements taken than available");
    while (n--) {
        var x = Math.floor(Math.random() * len);
        result[n] = arr[x in taken ? taken[x] : x];
        taken[x] = --len in taken ? taken[len] : len;
    }
    return result;
}