function ascending(a, b) {
  return a > b ? 1 : a < b ? -1 : 0;
}
Compare function sorting arrays in ascending order.  Safe to use for numeric values.
@param {*} a The first object to be compared.
@param {*} b The second object to be compared.
@return {number} A negative number, zero, or a positive number as the first
    argument is less than, equal to, or greater than the second.