js判断字符串是否有重复

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

//不重复
hash[arrStr[i]]=true;
}
else{

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