How to detect user is on page or not in VUEJS?

Question

Vue.js

How to understand on the page now the user or the tab in the background?
I do SPA but with a router and you can sit in 3/4 tabs in one application, there is a common method that from time to time sends something to the user in the form of a notification, I want to send a notification only to the tab in which the user is located or to which he will return first, how to determine this without jquery?

Answer 1

Use window.onfocus and window.onblur

Answer 2

https://www.google.com/search?q=active+window+java...