Proposal: Deprecate alert(), confirm(), prompt()
The alert(), confirm() and prompt() APis are more and more being used in malicious ways , such as keeping a user on the page and not allowing them to leave, mainly by web scams, or abusive advertising (usually by looping the alert box).
On Chrome (iOS) the situation was so bad i would have to restart the phone, as re-opening the browser would just reload the page. I belive this has now been fixed
Chromium’s latest policy no longer condones the usage of these Apis either
Here i haven’t included an infinite loop, but only 6 iterations to show what happens.
What is being done?
Chromium have blocked alerts() from being called in an unload handler but this isn’t enough, pages have got around this by starting the loop once you enter the page.
Chrome iOS have now added a supress option in their browser
Window.showModalDialog() has been deprecated and removed in hrome 43, and Firefox 55. 
The Notifications API is very useful and should be used for notifiying the user of events, and has good basic support across all modern browsers. For those needing to gain user input  should be used instead. I understand dialog is not well supported across modern browsers yet, Google have provided a polyfill untill this is the case https://github.com/GoogleChrome/dialog-polyfill.
Having dialogs native in the browser should reduce the concern of overhead (needing scripts, plugins just to show a confirmation/alert box).
With these alternatives in place, and a comprehensive set of tools in the web ecosystem i believe there is no need to ever use these APIs anymore and thus should be deprecated from the specification
Issue posted here: