Up until 2016-08-23, Service Workers were marked in MDN as experimental [1], despite the concentrated push by various parties to get people to stop using stuff like AppCache and use Service Workers instead.

That being said, at least Dialog is part of both the WHATWG HTML5 "Living Standard" (a fancy name for snapshot), and the W3C HTML 5.1 Recommendation, making it approved and finalized by both the practical body of rapidly-evolving browser makers and the political body that historically set web standards. In contrast, Service Workers are still a draft, despite having been pushed for years, and its predecessor technologies having largely been deprecated.

In other words, this is quite normal in the world of the Web Platform today, for better and for worse.

[1] https://developer.mozilla.org/en-US/docs/Web/API/Service_Wor...

I'd argue that any serious production app should still be using both AppCache and Service Worker. Heck, if you have AppCache setup and working already, why would you remove it? Service Worker isn't supported by Internet Explorer, Safari, or Firefox ESR. Those browsers can account for a large portion of the market, depending on your target demographic.

The <dialog> element is supported in even fewer browsers [0]! You can sorta polyfill it, but not perfectly.

[0] http://caniuse.com/#feat=dialog

Looks like <dialog> only works in blink so far, and it's not easily polyfilled unfortunatley

100% agreeing.

In 2017, not being able to have native dialog, a datepicker or a solid i18l for content is just sad.