检测网站（不是webapp！）是否已添加到主屏幕？

Question

I've added a JavaScript notification that reminds iOS users to 'Add to home screen' on some of my sites - it's designed so that it only triggers on the User's second visit to the site - but will continue to show after that regardless.

Is there a way to detect if the user already has this on their homescreen and prevent the notification popping up if they do? Also would there be a way that if they close the window, signalling that they don't want to add it, it doesn't come up again?

Answer 1

You can't know whether they've added you but you can know if they are looking at your site via launching it from home screen. To do this, simply check window.navigator.standalone .

Combine that with the best practice of not repeatedly prompting the user (set a cookie once you've prompted them and don't prompt them again until that cookie has expired) and you'll be alright.

Answer 2

You can store a value in a cookie and check if they have already visited the site and/or accepted the notification. Of course, the values would disappear if they clear their cache.

You can find more information on cookies with javascript at http://www.w3schools.com/js/js_cookies.asp