测试JavaScript字符串处理性能的代码

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)); 
 
注：循环次数必须足够大。