code: function copyArray(dst, src) {
    if (!src) return;
    var dstLength = dst.length;
    for (var i = src.length - 1; i >= 0; --i) {
      dst[i+dstLength] = src[i];
    }
  }
docs: Shallow-copies an array to the end of another array Basically Array.concat, but works with other non-array collections