create an Observable that emits a particular item after a given delay
 The Timer operator creates an Observable that emits one particular item after a span of time that you specify.
timer  RxGroovy implements this operator as timer.
  timer returns an Observable that emits a single number zero after a delay period you specify. 
 timer by default operates on the computation Scheduler, or you can override this by passing in a Scheduler as a final parameter. 
timer(long,TimeUnit)
timer(long,TimeUnit,Scheduler)
timer  RxJava implements this operator as timer.
  timer returns an Observable that emits a single number zero after a delay period you specify. 
 timer by default operates on the computation Scheduler, or you can override this by passing in a Scheduler as a final parameter. 
timer(long,TimeUnit)
timer(long,TimeUnit,Scheduler)
timer  In RxJS there are two versions of the timer operator.
  The first version of timer returns an Observable that emits a single item after a delay period you specify. You can specify the delay either as a Date object (which means, delay until that absolute moment) or as an integer (which means, delay that many milliseconds). 
  There is also a version of timer that returns an Observable that emits a single item after a specified delay, and then emits items periodically thereafter on a specified periodicity. In this way it behaves a bit more like the Interval operator. 
var source = Rx.Observable.timer(200, 100)
    .timeInterval()
    .pluck('interval')
    .take(3);
var subscription = source.subscribe(
    function (x) {
        console.log('Next: ' + x);
    },
    function (err) {
        console.log('Error: ' + err);
    },
    function () {
        console.log('Completed');
    });
Next: 200 Next: 100 Next: 100 Completed
 timer by default operates on the timeout Scheduler, or you can override this by passing in a Scheduler as a final parameter. 
 timer is found in each of the following distributions: 
rx.all.jsrx.all.compat.jsrx.time.js (requires either rx.js or rx.compat.js)rx.lite.jsrx.lite.compat.jstimer   RxPHP implements this operator as timer. 
Returns an observable sequence that produces a value after dueTime has elapsed.
//from https://github.com/ReactiveX/RxPHP/blob/master/demo/timer/timer.php $source = \Rx\Observable::timer(200); $source->subscribe($createStdoutObserver());
Next value: 0 Complete!
    © ReactiveX contributors
Licensed under the Apache License 2.0.
    http://reactivex.io/documentation/operators/timer.html