hash_depth.js

// (c) 2012 Usagi Ito / Wonder Rabbit Project <usagi@WonderRabbitProject.net>. License is MIT/X11.
var v = 'Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.';

var
  a1 =     [v],
  a2 =    [[v]],
  a3 =   [[[v]]],
  a4 =  [[[[v]]]],
  a5 = [[[[[v]]]]];

var benchmark = function(f, title){
  var a = new Date();
  for(var n = 100*1000*1000; n; --n)
    f();
  var b = new Date();
  console.log( { time:b-a, title:title } );
};

benchmark( function(){ var a = v;                 }, 'direct' );
benchmark( function(){ var a = a1[0];             }, 'array depth-1');
benchmark( function(){ var a = a2[0][0];          }, 'array depth-2');
benchmark( function(){ var a = a3[0][0][0];       }, 'array depth-3');
benchmark( function(){ var a = a4[0][0][0][0];    }, 'array depth-4');
benchmark( function(){ var a = a5[0][0][0][0][0]; }, 'array depth-5');

result:

LH-MAIN /tmp% node hash_depth.js
{ time: 1045, title: 'direct' }
{ time: 1155, title: 'array depth-1' }
{ time: 1503, title: 'array depth-2' }
{ time: 1636, title: 'array depth-3' }
{ time: 1905, title: 'array depth-4' }
{ time: 2106, title: 'array depth-5' }

LH-MAIN /tmp% node --version
v0.6.13

LH-MAIN /tmp% uname -a
Linux LH-MAIN 3.2.11-1-ARCH #1 SMP PREEMPT Thu Mar 15 09:19:02 CET 2012 x86_64 AMD Phenom(tm) II X4 940 Processor AuthenticAMD GNU/Linux

http://usagi.hatenablog.jp/entry/2012/04/06/195259

{ time: 109, title: 'direct' }
{ time: 116, title: 'array depth-1' }
{ time: 144, title: 'array depth-2' }
{ time: 169, title: 'array depth-3' }
{ time: 191, title: 'array depth-4' }
{ time: 201, title: 'array depth-5' }
{ time: 1400, title: 'with depth-0(direct)' }
{ time: 1396, title: 'with depth-0(array depth-1)' }
{ time: 1401, title: 'with depth-0(array depth-2)' }
{ time: 1469, title: 'with depth-0(array depth-3)' }
{ time: 1405, title: 'with depth-0(array depth-4)' }
{ time: 1396, title: 'with depth-0(array depth-5)' }
{ time: 94, title: 'direct in function scope' }
{ time: 93, title: 'array depth-1 in function scope' }
{ time: 94, title: 'array depth-2 in function scope' }
{ time: 97, title: 'array depth-3 in function scope' }
{ time: 94, title: 'array depth-4 in function scope' }
{ time: 93, title: 'array depth-5 in function scope' }
{ time: 115, title: 'array depth-1(5) in function scope' }
{ time: 151, title: 'array depth-2(5) in function scope' }
{ time: 170, title: 'array depth-3(5) in function scope' }
{ time: 191, title: 'array depth-4(5) in function scope' }
{ time: 211, title: 'array depth-5(5) in function scope' }

http://usagi.hatenablog.jp/entry/2012/04/06/205944