Display alert only once

Question

I have this code that shows alert when it\'s 30 minutes before event in calendar but I want to show it only once when user comes to page (in that 30min). Now it shows on eve

Answer 1

You have to use cookies or localStorage or sessionStorage to do this!

See the following link on localStorage: http://www.w3schools.com/html/html5_webstorage.asp

or

http://www.webdesignerdepot.com/2013/04/how-to-use-local-storage-for-javascript/