How to Display Firebase Posts in Descending Order by Posting Time?

Retrieve Firebase Posts in Descending Order

Firebase users often face the challenge of displaying posts in descending order based on their posting time. This tutorial addresses this need, explaining two methods for achieving this.

Method 1: Adding an Inverted Timestamp

Firebase allows ordering by child properties or value. To achieve descending order, add a "timestamp" child with the inverted timestamp (e.g., 0 - Date.now()). This will naturally sort the posts chronologically in reverse order.

var item = ref.push();
item.setWithPriority(yourObject, 0 - Date.now());

Method 2: Inverting on the Client

If adding a timestamp property is not feasible, retrieve the children in ascending order and invert them using client-side code.

fbl.child('sell').limit(20).on("value", function(fbdata) { 
  var comments = fbdata.exportVal();
  comments.reverse();
});

Updated Retrieval Syntax

When using Method 1, retrieve the data differently:

fbl.child('sell').startAt().limitToLast(20).on('child_added', function(fbdata) {
  console.log(fbdata.exportVal());
})

Example Implementation

See the following bin to demonstrate the implementation: http://jsbin.com/nonawe/3/watch?js,console

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