Bulk rename layers in illustrator by selected index

Layer renamer

var LayerRenamer, layerRenamer;

function range(start, end) {
  var foo = [];
  for (var i = start; i <= end; i++) {
      foo.push(i);
  }
  return foo;
}

LayerRenamer = (function() {
  function LayerRenamer() {
    if (app.activeDocument.selection.length > 0) {
      this.replacements = prompt('Replacement Strategy? EG: "a" OR "1" (starting number) OR coma separated custom values ab,cd,ef,gh... 1,3,5,7,8,9 ', 1)
      if (!this.replacements) return
      this.renameLayers(app.activeDocument.selection);
    } else {
      alert("Select the layers you would like to be renamed.");
    }
  }

  LayerRenamer.prototype.renameLayers = function(layers) {
    var layer, _i, _len, _results, customArr;
    _results = [];
    for (_i = 0, _len = layers.length; _i < _len; _i++) {
      layer = layers[_i];
      type = this.replacements
      customArr = type.split(',')
      if (customArr && customArr.length >= 5) {
        type = customArr
      } else if (type === 'a') {
        type = ['A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'];
      } else if (typeof (+type) === 'number') {
        type = range(type, type + 999)
      } else {
        type = range(type, type + 999)
      }
      _results.push(layer.name = typeof type[_i] !== 'undefined' ? type[_i] : _i);
    }
    return _results;
  };

  return LayerRenamer;

})();

layerRenamer = new LayerRenamer();