<script>
          /**
           *  첫번째 탭 유저리스트 호출
           */
          FirebaseChat.prototype.loadUserList = function(){
              //...생략
              var cbCompleteUserList = function(){
                  this.loadOnlineStatus();
              }
              userRef.orderByChild("userName")
                  .once('value', this.getUserList.bind(this))
                  .then(cbCompleteUserList.bind(this));
          }

          /**
           * 유저의 온라인 여부 감지하여 유저리스트에 표시 해주는 기능
           */
          FirebaseChat.prototype.loadOnlineStatus = function(){
              var usersConnectionRef = this.database.ref('UsersConnection');
              usersConnectionRef.off();
              var cbUserConnection = function(data){
                  var connKey =data.key;
                  var connValue = data.val();
                  var onlineIcon = document.querySelector('#li' + connKey+' .mood');
                  if(onlineIcon != null){
                      if(connValue.connection === true){
                          onlineIcon.classList.remove('hiddendiv');
                      }else{
                          onlineIcon.classList.add('hiddendiv');
                      }
                  }
              }
              usersConnectionRef.on('child_added', cbUserConnection.bind(this));
              usersConnectionRef.on('child_changed', cbUserConnection.bind(this));
          }