Delays the emission of items from the source Observable by a given timeout or until a given Date.
例子:
const clicks = fromEvent(document, 'click');
const delayedClicks = clicks.pipe(delay(1000)); // each click emitted after 1 second
clicks.subscribe(x => console.log('diablo normal: ' + x));
delayedClicks.subscribe(x => console.log('diablo delayed: ' + x));
测试结果:
delayed Observable emit value的时间戳总是比normal Observable晚一秒钟。