mapTo
Emits the given constant value on the output Observable every time the source Observable emits a value.
mapTo<T, R>(value: R): OperatorFunction<T, R>Parameters
| value |
The value to map each source value to. |
Returns
OperatorFunction<T, R>: An Observable that emits the given value every time
the source Observable emits something.
Description
Like map, but it maps every source value to
the same output value every time.
Takes a constant value as argument, and emits that whenever the source
Observable emits a value. In other words, ignores the actual source value,
and simply uses the emission moment to know when to emit the given value.
Example
Map every click to the string 'Hi'
import { fromEvent } from 'rxjs';
import { mapTo } from 'rxjs/operators';
const clicks = fromEvent(document, 'click');
const greetings = clicks.pipe(mapTo('Hi'));
greetings.subscribe(x => console.log(x));