Chromium policy on JavaScript dialogs
Synchronous, app-modal JavaScript dialogs are commonly (and unfortunately) used to harm users. Because of this, the Chromium team highly recommends that you not use JavaScript dialogs.
dialog element shipped in Chrome 37 Beta
Chrome Beta has landed its native support for <dialog> element
dialog element: Modals made easy
Have you ever created your own modal dialog box? Soon, you won't need to ever again; dialog boxes are becoming a part of the web platform.
