This lesson introduces operators empty(), never(), and throw(), which despite being plain and void of functionality, are very useful when combining with other Observables.
empty:
var foo = Rx.Observable.empty(); // the same as var foo = Rx.Observable.create( function(observe) { observe.complete(); }) foo.subscribe(function (x) { console.log(‘next ‘ + x); }, function (err) { console.log(‘error ‘ + err); }, function () { console.log(‘done‘); }); //done
never(): do nothing
var foo = Rx.Observable.never(); // the same as var foo = Rx.Observable.create( function(observe) { }) foo.subscribe(function (x) { console.log(‘next ‘ + x); }, function (err) { console.log(‘error ‘ + err); }, function () { console.log(‘done‘); });
throw(): throw a Javascript error
var foo = Rx.Observable.throw(new Error(‘blooom‘)); // the same as var foo = Rx.Observable.create( function(observe) { observe.error(‘bloom‘); }) foo.subscribe(function (x) { console.log(‘next ‘ + x); }, function (err) { console.log(‘error ‘ + err); }, function () { console.log(‘done‘); });
[RxJS] Creation operators: empty, never, throw
原文：http://www.cnblogs.com/Answer1215/p/5389550.html