range.js

function range(/* [begin,] end[, step] */) {
  var begin = arguments.length > 1 ? arguments[0] : 0,
      end = arguments.length > 1 ? arguments[1] : arguments[0],
      step = arguments[2] || 1,
      n = Math.max(0, Math.ceil((end - begin) / step))
  return Array.apply(null, Array(n)).map(function (_, i) {
    return begin + step * i
  })
}