function cutstr(str ,len){
var temp,
icount = 0,
patrn =/[^\x00-\xff]/,
strre = "";
for(var i = 0; i< str.length; i++){
if(icount < len -1){
temp = str.substr(i,1);
if(patrn.exec(temp) == null) {
icount = icount + 1;
}else{
icount= icount +2;
}
strre += temp;
}else{
break;
}
}
return strre + "...";
}
原文：http://www.cnblogs.com/chouchoujun/p/5980313.html