js判斷字符串是否有重復

//判斷字符串是否有重復
function IsRepeat(lessonName){
var repeatName="";
var hash = {};
var arrStr=lessonName.split(',');
for(var i=0;i<arrStr.length;i++){
if(!hash[arrStr[i]])
{

//不重復
hash[arrStr[i]]=true;
}
else{

//重復
repeatName+=arrStr[i]+"、";
}
}
if(repeatName!=""){
alert("XX："+repeatName.substring(0,repeatName.length-1)+"存在重復！");
}
}