String.prototype.repeat

[Sunny]

 String.prototype.repeat= function (n) {
    let str = this;
    let res = ''
    while (n) {
        res += str;
        n--
    }
    return res
}
console.log('abc'.repeat(3));

[kangkang123269]

String.prototype.repeat = function(count) {
  if (count < 0) {
    throw new RangeError("Count must be non-negative");
  }

  let repeatedString = "";
  for (let i = 0; i < count; i++) {
    repeatedString += this;
  }
  return repeatedString;
};