Proposed Chromium policy on JavaScript dialogs  |  Web  |  Google Developers

Chromium is advising developers to not use alert(), confirm(), and prompt() methods in JavaScript anymore, and, in the future, they might even deprecate sites that still use them. The suggestion is to use the Web Notification API instead, in the hope that its asynchronous nature will prevent it from being misused against users. As a nice side effect, using the API will also speed up browser performance significantly.