Array.prototype.fill()

[1, 2, 3].fill(4); // [4, 4, 4]
[1, 2, 3].fill(4, 1); // [1, 4, 4]
[1, 2, 3].fill(4, 1, 2); // [1, 4, 3]
[1, 2, 3].fill(4, 1, 1); // [1, 2, 3]
[1, 2, 3].fill(4, -3, -2); // [4, 2, 3]
[1, 2, 3].fill(4, NaN, NaN); // [1, 2, 3]
Array(3).fill(4); // [4, 4, 4]
[].fill.call({ length: 3 }, 4); // {0: 4, 1: 4, 2: 4, length: 3}

if (!Array.prototype.fill) {
  Array.prototype.fill = function (value) {
    // Passo 1-2.
    if (this == null) {
      throw new TypeError("this is null or not defined");
    }

    var O = Object(this);

    // Passo 3-5.
    var len = O.length >>> 0;

    // Passo 6-7.
    var start = arguments[1];
    var relativeStart = start >> 0;

    // Passo 8.
    var k =
      relativeStart < 0
        ? Math.max(len + relativeStart, 0)
        : Math.min(relativeStart, len);

    // Passo 9-10.
    var end = arguments[2];
    var relativeEnd = end === undefined ? len : end >> 0;

    // Passo 11.
    var final =
      relativeEnd < 0
        ? Math.max(len + relativeEnd, 0)
        : Math.min(relativeEnd, len);

    // Passo 12.
    while (k < final) {
      O[k] = value;
      k++;
    }

    // Passo 13.
    return O;
  };
}