Is there an RX method which combines map and filter?

问题

I'm new to RxJS. I know I could just .filter and .map an observable to get the change I'm looking for. But, is there any method which combines the two into one function?

回答1:

Yes there is.

FlatMap.

Suppose you have an Observable of numbers (1, 2, 3, 4, 5, ...) and you want to filter for even numbers and map them to x*10.

var tenTimesEvenNumbers = numbers.flatMap(function (x) {
  if (x % 2 === 0) {
    return Rx.Observable.just(x * 10);
  } else {
    return Rx.Observable.empty();
  }
});

来源：https://stackoverflow.com/questions/32446977/is-there-an-rx-method-which-combines-map-and-filter