Here's a sample code snippet:
Firebase Database
name: Sonic
when changed value
name: Sonita
FirebaseRef.on('value', function(snapshot) {
var previousName = ?; //Sonic
var newName = snapshot.val(); //Sonita
});
Here's a sample code snippet:
Firebase Database
name: Sonic
when changed value
name: Sonita
FirebaseRef.on('value', function(snapshot) {
var previousName = ?; //Sonic
var newName = snapshot.val(); //Sonita
});
If you're looking to access the previous value of a node when it changes, Firebase does not offer a direct solution for this. You will need to store the previous value somewhere yourself.
One approach is to save the previous value as a child node. Here's how you can do it:
1) When updating the value:
var new_name = "Sonich";
FireBaseRef.once('value', function(snapshot) {
var prev_name= snapshot.val(); // Previous value
FireBaseRef.set({
"value": new_name,
"prev_value": prev_name
});
});
2) To retrieve the values:
FireBaseRef.on('value', function(snapshot) {
snapshot = snapshot.val();
var previous_name = snapshot.prev_value;
var new_name = snapshot.value;
});
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