var startdate = 1552268459655;
var enddate = 1552268535866;
    firebase.database().ref().child("Perangkat2").child("hujan").child("2").child("hujanpermenit").child(data.key).orderByChild("timestamp").startAt(startdate).endAt(enddate).once('value').then(function(snapshot) {
snapshot.forEach(function(child) {
var childData = child.val();
var timestamps=child.val().timestamp;
var nilai=child.val().nilai;
   });
});