examples-array-ify.js

// testing converting arguments to an Array

function manualMap () {
  var l = arguments.length
  var arr = new Array(l)
  for (var i = 0; i < l; i ++) arr[i] = arguments[i]
  return arr
}

function manualMapArg (x) {
  var l = arguments.length
  var arr = new Array(l)
  for (var i = 0; i < l; i ++) arr[i] = arguments[i]
  return arr
}

function duff () {
  var l = arguments.length
  var arr = new Array(l)
  switch (l) {
    case 8: arr[7] = arguments[7]
    case 7: arr[6] = arguments[6]
    case 6: arr[5] = arguments[5]
    case 5: arr[4] = arguments[4]
    case 4: arr[3] = arguments[3]
    case 3: arr[2] = arguments[2]
    case 2: arr[1] = arguments[1]
    case 1: arr[0] = arguments[0]
  }
  return arr
}

function from () {
  return Array.from(arguments)
}

function arrayApplyProto () {
  return Array.apply(Object.create(Array.prototype), arguments)
}

function arrayApplyNull () {
  return arguments.length === 1 ? [arguments[0]] : Array.apply(null, arguments)
}

function arrayApplyArg (x) {
  return arguments.length === 1 ? [arguments[0]] : Array.apply(null, arguments)
}

function sliceCall () {
  return Array.prototype.slice.call(arguments)
}

function sliceCallArg (x) {
  return Array.prototype.slice.call(arguments)
}

function sliceZeroCall () {
  return Array.prototype.slice.call(arguments, 0)
}

function sliceZeroCallArg (x) {
  return Array.prototype.slice.call(arguments, 0)
}

function sliceApply () {
  return Array.prototype.slice.apply(arguments)
}

function sliceApplyArg (x) {
  return Array.prototype.slice.apply(arguments)
}

function sliceZeroApply () {
  return Array.prototype.slice.apply(arguments, [0])
}

function sliceZeroApplyArg (x) {
  return Array.prototype.slice.apply(arguments, [0])
}

function arrayProto () {
  arguments.__proto__ = Array.prototype
  return arguments
}

function splat (...args) {
  return args
}

exports.compare =
  { manualMap: function () {
      return [ manualMap(Math.random()), manualMap(Math.random(), Math.random()) ]
    }
  , splat: function () {
      return [ splat(Math.random()), splat(Math.random(), Math.random()) ]
    }
  , arrayProto: function () {
      return [ arrayProto(Math.random()), arrayProto(Math.random(), Math.random()) ]
    }
  , duff: function () {
      return [ duff(Math.random()), duff(Math.random(), Math.random()) ]
    }
  , arrayApplyNull: function () {
      return [ arrayApplyNull(Math.random()), arrayApplyNull(Math.random(), Math.random()) ]
    }
  , manualMapArg: function () {
      return [ manualMapArg(Math.random()), manualMapArg(Math.random(), Math.random()) ]
    }
  , arrayApplyArg: function () {
      return [ arrayApplyArg(Math.random()), arrayApplyArg(Math.random(), Math.random()) ]
    }
  , sliceCall: function () {
      return [ sliceCall(Math.random()), sliceCall(Math.random(), Math.random()) ]
    }
  , sliceCallArg: function () {
      return [ sliceCallArg(Math.random()), sliceCallArg(Math.random(), Math.random()) ]
    }
  , sliceZeroCall: function () {
      return [ sliceZeroCall(Math.random()), sliceZeroCall(Math.random(), Math.random()) ]
    }
  , sliceZeroCallArg: function () {
      return [ sliceZeroCallArg(Math.random()), sliceZeroCallArg(Math.random(), Math.random()) ]
    }
  , sliceApply: function () {
      return [ sliceApply(Math.random()), sliceApply(Math.random(), Math.random()) ]
    }
  , sliceApplyArg: function () {
      return [ sliceApplyArg(Math.random()), sliceApplyArg(Math.random(), Math.random()) ]
    }
  , sliceZeroApply: function () {
      return [ sliceZeroApply(Math.random()), sliceZeroApply(Math.random(), Math.random()) ]
    }
  , sliceZeroApplyArg: function () {
      return [ sliceZeroApplyArg(Math.random()), sliceZeroApplyArg(Math.random(), Math.random()) ]
    }
  }

exports.countPerLap = 2

require("../").runMain()

gistfile.txt

benchmarking /Users/isaacs/dev/js/bench/examples/array-ify.js
Please be patient.
{ http_parser: '2.7.0',
  node: '8.0.0-pre',
  v8: '5.5.372.40',
  uv: '1.10.2',
  zlib: '1.2.8',
  ares: '1.10.1-DEV',
  modules: '52',
  openssl: '1.0.2k',
  icu: '58.2',
  unicode: '9.0',
  cldr: '30.0.3',
  tz: '2016j' }
Scores: (bigger is better)

manualMap
Raw:
 > 42559.44055944056
 > 43014.98501498502
 > 43156.843156843155
 > 43244.755244755244
Average (mean) 42994.005994005995

duff
Raw:
 > 46215.78421578422
 > 38681.318681318684
 > 42429.57042957043
 > 37818.181818181816
Average (mean) 41286.21378621379

splat
Raw:
 > 38399.6003996004
 > 37670.32967032967
 > 38899.1008991009
 > 34621.37862137862
Average (mean) 37397.6023976024

manualMapArg
Raw:
 > 21992.00799200799
 > 29142.85714285714
 > 29153.692614770458
 > 25732.267732267734
Average (mean) 26505.206370475833

arrayApplyNull
Raw:
 > 10325.674325674325
 > 10081.918081918082
 > 9296.703296703297
 > 9586.413586413586
Average (mean) 9822.677322677322

arrayApplyArg
Raw:
 > 9356.643356643357
 > 9344.655344655344
 > 7850.14985014985
 > 9098.901098901099
Average (mean) 8912.587412587412

sliceApply
Raw:
 > 6769.2307692307695
 > 6929.070929070929
 > 5508.491508491508
 > 6711.288711288711
Average (mean) 6479.520479520479

sliceZeroApply
Raw:
 > 6285.714285714285
 > 6427.572427572428
 > 6225.774225774226
 > 6367.632367632367
Average (mean) 6326.673326673326

sliceCall
Raw:
 > 6825.174825174825
 > 5830.339321357285
 > 6047.952047952048
 > 6423.576423576424
Average (mean) 6281.760654515145

sliceCallArg
Raw:
 > 6115.884115884116
 > 5834.165834165834
 > 5858.141858141858
 > 6057.9420579420575
Average (mean) 5966.533466533467

arrayProto
Raw:
 > 5836.163836163836
 > 5668.331668331668
 > 5982.017982017982
 > 5924.075924075924
Average (mean) 5852.647352647353

sliceApplyArg
Raw:
 > 6079.92007992008
 > 5272.727272727273
 > 5802.197802197802
 > 5810.1898101898105
Average (mean) 5741.258741258742

sliceZeroCall
Raw:
 > 5202.797202797203
 > 6551.448551448551
 > 5230.7692307692305
 > 5970.02997002997
Average (mean) 5738.761238761238

sliceZeroCallArg
Raw:
 > 4893.106893106893
 > 5680.319680319681
 > 5664.335664335665
 > 5496.5034965034965
Average (mean) 5433.566433566434

sliceZeroApplyArg
Raw:
 > 5354.645354645355
 > 5102.897102897103
 > 5666.333666333667
 > 5442.557442557442
Average (mean) 5391.608391608392

Winner: manualMap
Compared with next highest (duff), it's:
3.97% faster
1.04 times as fast
0.02 order(s) of magnitude faster
A LITTLE FASTER

Compared with the slowest (sliceZeroApplyArg), it's:
87.46% faster
7.97 times as fast
0.9 order(s) of magnitude faster