JavaScript文字列の処理性能をテストするコード

 
  
var oldtime = new Date().getTime(); 
  
var str = []; 
  
for(i=0;i<100000;i++) 
  
{ 
  
str.push('abcabcabcabcabcabcabcabcabcabcabcabc'); 
  
} 
  
var newtime = new Date().getTime(); 
  
var joinTime = (newtime - oldtime); 
  
 
  
var oldtime = new Date().getTime(); 
  
var str=''; 
  
for(i=0;i<100000;i++) 
  
{ 
  
str += 'abcabcabcabcabcabcabcabcabcabcabcabc'; 
  
} 
  
var newtime = new Date().getTime(); 
  
var concatTime = (newtime - oldtime); 
  
 
  
alert("join / concat: " + (joinTime * 1.0 / concatTime));