fast_repeatString.js

function repeatString(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;
};