Rxjs5，distinct（）无法正常工作

Question

This is the code:

if you inject the do() before the distinct() operator everything is working

just fine, but for some reasons distinct() print only the first object

_

Rx.Observable
  .interval(1000)
  .flatMap(_ => { // JSONP request
    return Rx.Observable.create(observer => {
      window.eqfeed_callback = res => {
        observer.next(res);
        observer.complete();
      };

      loadJSONP(QUAKE_URL);
    }).retry(3);
  })
  .flatMap(res => Rx.Observable.from(res.features))
  .map(quake => {
    return {
      lat: quake.geometry.coordinates[1],
      lng: quake.geometry.coordinates[0],
      size: quake.properties.mag * 10000,
      code: quake.properties.code
    };
  })
  .do(logToConsole) // DEBUG: all objects are logged to the console
  .distinct(quake => quake.code) // it only log the first object !
  .subscribe(logToConsole);

Answer 1

Based on the function description provided by reactivex.io, my understanding is that the .distinct() operator should in fact work the way you have coded (whether this is a bug or not, I am unsure).

However, seeing as your code does not work (as I have tested it also), another option is to use .pluck() to pull out the value before calling .distinct() . In my testing, this will now work as expected (do not provide any arguments to the .distinct() call).

Example based on your code:

.do(logToConsole) // DEBUG: all objects are logged to the console
.pluck("code")
.distinct() // now works as expected
.subscribe(logToConsole);`