javascript - Register Firebase Listener Without Calling It? -

is possible register firebase listener function without calling when register it?

for example:

this.gamestateurl.on('value', function(snapshot){     self.gamestatechangeevent(snapshot); }); 

gamestatechangeevent function fires upon setting listener.

thank you.

unfortunately, no. docs state:

this event trigger once initial data stored @ location, , trigger again each time data changes. datasnapshot passed callback location @ on() called. won't trigger until entire contents has been synchronized. if location has no data, triggered empty datasnapshot (val() return null).

you could, this:

var ref = this.gamestateurl // or create ref  function dosomethingwithaddedorchangedsnapshot(snapshot) {      // function called whenever child added      // or changed }  // assuming have "timestamp" property on these objects // not called snapshots on initialization // because timestamp of existing snapshots not greater // current time ref.orderbychild('timestamp')    .startat(new date().gettime())    .on('child_added', dosomethingwithaddedorchangedsnapshot);  ref.on('child_changed', dosomethingwithaddedorchangedsnapshot);  ref.once('value', function(snapshot){     // initial state once     // snapshot represents items on ref     // fire once on initialization     initializegamedata(snapshot.val()); }); 

in english:

• create 1 function handles updated/added child
• start listening child_added event children added after current timestamp (unix time since epoch). assumes you're storing timestamp on these children.
• start listening child_changed event child changed.
• grab values of ref once initialize data.
• not sure if use case needs handle 'child_removed' or 'child_moved'