js关于字符长度限制的问题示例探讨

var fun = function(str){ 
var preg = new RegExp("[\u4e00-\u9fa5]+","gi"); 
var preg2 = new RegExp("[^\u4e00-\u9fa5]","gi"); 
var count = 0; 
for(var i=0;i<str.length;i++){ 
if(preg.test(str[i])){ 
count = count+2; 
}else{ 
count = count+1; 
} 
} 
return count; 
}