Wilddog:只获取新增的数据

limit_endat.js

// when  the records is empty ,it not work
var ref = new Wilddog(...);
var first = true;
ref.limitToLast(1).on("child_added", function(snap) {
  if( first ) {
   first = false; 
  } 
  else {
   console.log('new record', snap.key());
  }
});

once_value.js

var ref = new Wilddog(...);
ref.once("value", function(snap) {
  var keys = Object.keys(snap.val()||{});
  var lastIdInSnapshot = keys[keys.length-1]

  ref.orderByKey().startAt(lastIdInSnapshot).on("child_added", function(newMessSnapshot) {
    if( snap.key() === lastIdInSnapshot ) { return; }
        console.log('new record', newMessSnapshot.key());
    })
})

query_timestamp.js

// assumes you add a timestamp field to each record (see Wilddog.ServerValue.TIMESTAMP)
// pros: fast and done server-side (less bandwidth, faster response), simple
// cons: a few bytes on each record for the timestamp
var ref = new Wilddog(...);
ref.orderByChild('timestamp').startAt(Date.now()).on('child_added', function(snapshot) {
  console.log('new record', snapshot.key());
});