blink_mapto.ts

const show$ = Observable.timer(0, 1000);
const hide$ = Observable.timer(750, 1000);

const blinker$ = Observable.merge(
  show$.mapTo('showing'),
  hide$.mapTo('hiding')
);

blinker$.subscribe(value => console.log(value));


// Delay:    Output:
/*   0 ms */ showing
/* 750 ms */ hiding
/* 250 ms */ showing
/* 750 ms */ hiding
/* 250 ms */ showing
/* 750 ms */ hiding
/* 250 ms */ showing
/* 750 ms */ hiding
/*  ...   */