Array.prototype.myCopyWithin = function(target, start, end) {
    const o = Object(this);
    const len = o.length | 0;

    const relativeTarget = target | 0;
    const to = relativeTarget >= 0 ?
    Math.min(relativeTarget, len) : Math.max(len + relativeTarget, 0);

    const relativeStart = start | 0;
    const from = relativeStart >= 0 ?
    Math.min(relativeStart, len) : Math.max(len + relativeStart, 0);

    const relativeEnd = end ? end | 0 : len;
    const final = relativeEnd >= 0 ?
    Math.min(relativeEnd, len) : Math.max(len + relativeEnd, 0);

    const copy = JSON.parse(JSON.stringify(o));

    (function copyElements(t, s, e) {
        if (s < e && t < len) {
            o[t] = copy[s];
            copyElements(t + 1, s + 1, e);
        }
        return o;
    })(to, from, final);

    return o;
};