lastOrDefault - richardszalay/raix GitHub Wiki

Emits the last value from a source sequence or the default value if the source sequence is empty.

function lastOrDefault() : IObservable.<T>

If the source sequence is empty, the default value for the sequence type will be emitted. The value will be 0 for numbers, false for Boolean, and null for all other values.

The returned sequence completes when the source sequence completes.

The returned sequence errors when the source sequences errors

xs = source
ys = output

xs  ──o───o─o────o──/
                 │
                 └──┐
                    │
ys  ────────────────o/


xs  ────────────────/
                    │
                    │
                    │
ys  ────────────────o
               0/false/null

IObservable.<T>

var source : IObservable = Observable.empty()
    .lastOrDefault();

source.subscribe(
    function(value : int) : void { trace(value; },
    function() : void { trace("Completed!"); }
    );

// Trace output is:
// 0
// Completed!