repeatString discovery.js

function repeatStringBinary(str, how_many)
{
  how_many|=0; // convert to number and round
  str+=""; // convert to string
  
  if(how_many<=0 || str.length==0)
    return "";
  if(how_many==1)
    return str;
  if(how_many==2)
    return str+str;
    
  var result="";
  
  while(how_many)
  {
    if(how_many&1)
      result+=str;
      
    how_many>>=1;
    str+=str;
  }
  
  return result;
};

function repeatStringLinear(str, how_many) {
  var result = '';
  for (var i = 0; i < how_many; i++) 
  result += str;
  return result;
}

var i,n=100000;
var a="a",m=100;

function _clear(a,m,n)
{
  var i,d0=+new Date();
  
  for(i=0;i<n;++i)
    ;
  
  return new Date()-d0;
};  
function _linear(a,m,n)
{
  var i,d0=+new Date();
  
  for(i=0;i<n;++i)
    repeatStringLinear(a,m);
  
  return new Date()-d0;
};  
function _binary(a,m,n)
{
  var i,d0=+new Date();
  
  for(i=0;i<n;++i)
    repeatStringBinary(a,m);
  
  return new Date()-d0;
};  

if(window.console==null)
  window.console={};
if(console.log==null)
  console.log=function(msg){ alert(msg); };


function _pointTest(a,m,n)
{
  var clear=_clear(a,m,n);
  
  console.log("linear "+(_linear(a,m,n)-clear));
  console.log("binary "+(_binary(a,m,n)-clear));
};  

function _linearTest(a,n,x,y,step)
{
  var clears=[];
  
  for(var m=x;m<y;m+=step)
    clears.push(_clear(a,m,n));
  
  var t="";
  
  for(var m=x;m<y;m+=step)
    t+=m+"\t";
    
  console.log("m\t\t "+t);
  t="";
  
  for(var m=x,i=0;m<y;m+=step,++i)
    t+=(_linear(a,m,n)-clears[i])+"\t";
  
  console.log("linear\t\t "+t);

  t="";
  
  for(var m=x,i=0;m<y;m+=step,++i)
    t+=(_binary(a,m,n)-clears[i])+"\t";
  
  console.log("binary\t\t "+t);
};

function _binaryTest(a,n,x,y,step)
{
  var clears=[];
  
  for(var m=x;m<y;m*=step)
    clears.push(_clear(a,m,n));
    
  var t="";
  
  for(var m=x;m<y;m*=step)
    t+=m+"\t";
    
  console.log("m\t\t "+t);
  t="";
  
  for(var m=x,i=0;m<y;m*=step,++i)
    t+=(_linear(a,m,n)-clears[i])+"\t";
  
  console.log("linear\t\t\ "+t);
  
  t="";
  
  for(var m=x,i=0;m<y;m*=step,++i)
    t+=(_binary(a,m,n)-clears[i])+"\t";
  
  console.log("binary\t\t "+t);
};


//_pointTest("a",3,100000);
/*
ff3.6
linear 723
binary 861

chrome 4.0.249.89 (38071)
linear 188
binary 165

ie7
linear 1482
binary 1933

opera 10.10
linear 501
binary 1111

opera 10.50
linear 208
binary 218
*/

//_linearTest("a",20000,1,16,2);
/*
ff3.6
m 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
linear 115 114 122 142 159 175 179 208 216 222 246 250 266 271 296
binary 85 111 216 248 245 231 229 216 236 226 263 233 257 250 273 

chrome 4.0.249.89 (38071)
m		 1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	
linear		 16	16	22	31	37	39	44	48	53	62	67	69	80	84	91	
binary		 13	19	34	33	39	32	48	41	41	46	48	42	51	47	52	

ie7 _linearTest("a",5000,1,16,2);
m 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 
linear 80 100 90 80 100 120 131 130 150 180 181 190 190 210 231 
binary 50 60 100 90 110 111 120 110 130 130 140 121 130 140 140 

opera 10.10
m 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 
linear 60 40 231 70 250 90 291 120 300 301 330 161 350 341 360 
binary 231 50 110 300 301 130 320 301 320 311 350 321 340 331 340 

opera 10.50
m		 1	3	5	7	9	11	13	15	
linear		 8	32	45	57	85	90	101	115	
binary		 7	41	53	66	53	78	76	92	
*/

//_binaryTest("a",20000,1,129,2);
/*
ff3.6
m 1 2 4 8 16 32 64 128
linear 144 104 143 199 305 511 910 1778
binary 85 104 182 217 244 275 566 374 

chrome 4.0.249.89 (38071)
m		 1	2	4	8	16	32	64	128	
linear		 15	16	29	49	100	180	377	736	
binary		 13	20	31	40	46	50	56	74

ie7 _binaryTest("a",5000,1,129,4);
m 1 4 16 64 
linear 80 130 260 882 
binary 50 100 130 150 

opera 10.10
m 1 2 4 8 16 32 64 128 
linear 50 40 81 270 381 701 1362 2493 
binary 70 30 291 300 341 340 551 911

opera 10.50
m		 1	2	4	8	16	32	64	128	
linear		 7	18	29	63	121	226	423	815	
binary		 7	18	41	56	67	73	100	154	
*/