字符串去重，并去除掉特殊字符按照数字在前字母在后的顺序排序字符串

var str = "1233fddfd&3434fdsaff&454545&4545444rfdsfds&545gdsgs";
 var n = "";
 var s="";
for(var i=0;i<str.length;i++){
    if((str[i]>=0&&str[i]<=9)&&n.indexOf(str[i])==-1){
        n+=str[i];
    }else if((str.charCodeAt(i)>=97&&str.charCodeAt(i)<=122)&&s.indexOf(str[i])==-1){
        s+=str[i];
    }
}
console.log(n+s); //12345fdsarg