Measuring a duration of execution in Node.js

measuringDuration.coffee

##
# Utility function to measure time intervals. Polymorphic return value:
#
# * returns either the current high-resolution real time, given no argument;
# * or the time elapsed since a given high-resolution real time, that was
#   retrieved from a previous call to this function.
#
# Usage:
#   t0 = hrtime()
#   duration = hrtime( t0)   # expressed in milliseconds
#
# See also:
#   [Node.js API › process.hrtime()](https://nodejs.org/api/process.html#process_process_hrtime)
#
hrtime = (since) ->
  return process.hrtime() unless since?
  end = process.hrtime( since)
  Math.round(( end[ 0] * 1e3) + ( end[ 1] / 1e6))