Am I using ForEach correctly?

firebase

Solution

You cannot `forEach` over a ref, but only over a snapshot.

   // for each user that is online, output to the console
   gameRef.on('value', function(function(gamesSnapshot) {
       gamesSnapshot.forEach(function (snapshot) {
           var obj = snapshot.val();
           if(obj.isOnline == true) {
               console.log(obj.name + " is online.");
           }
       }
   });

This code has two snapshot variables:

- `gameSnapshot` is the data in the parent node

- `snapshot` is the data of a specific player

Alternative

The approach above will download all players, even though you are only looking to deal with players that are online. It is more efficient in this case, to query Firebase so that it only returns players that are online.

   // for each user that is online, output to the console
   var onlinePlayers = gameRef.orderByChild('isOnline').equalTo(true);
   onlinePlayers.on('child_added', function(function(snapshot) {
       var obj = snapshot.val();
       if(obj.isOnline == true) {
           console.log(obj.name + " is online.");
       }
   });

The code now listens for the `child_added` event, since Firebase spoon-feeds us the players one at a time. You will probably also have to handle `child_changed` and `child_removed`, once you map the players to HTML elements.

Even though this will result in a bit more code, I would normally recommend using querying and the `child_*` events, since they limit the data that Firebase sends you both initially and when e.g. a player goes offline.

Problem

I'm working on a presence-like system in firebase with following layout: ``` firebase { user1 { isOnline: true } user 2 { isOnline: true } user3 { isOnline: false } } ``` The isOnline booleans are what I am going to use later to output the names of the users that are online to the console So for example, in the case above it would say: ``` user1 is online. user2 is online. ``` Here is my code: ``` var gameRef = new Firebase("https://xxx.firebaseio.com/"); var userOnline = new Firebase('https://xxx/.info/connected'); userOnline.on('value', function (snapshot) { if (snapshot.val()) { gameRef.child(user).update({ isOnline : true }); } else { gameRef.child(user).update({ isOnline : false }); } }); // for each user that is online, output to the console gameRef.forEach(function (snapshot) { var obj = snapshot.val(); if(obj.isOnline == true) { console.log(obj.name + " is online."); } }); ``` There seems to be a problem with my forEach, how can I fix this? Thanks.

Original source