Do something before reload or close in vue.js

What is it that "closes" or "reloads" the app? Is it the user in the browser closing the window and/or refreshing the page?

If that is the case, nothing is "destroyed" and that function won't run.

You would have to define a onbeforeunload function globally:

window.onbeforeunload = function(){
    return "Are you sure you want to close the window?";
}

Then you can save items to local storage inside that function before the return statement.

Note: don't define it inside your beforeDestroy function, because again, that just won't run when you reload the page or navigate away.