offline, cross-tab communication (javascript-only)

Question

Is it possible to find foreign instances of certain website? Ofc theese are independently opened tabs (not by window.open). I need to prevent user from opening 2 tabs, and s

Answer 1

localStorage can be used to track windows. You should take into account a situation when window crashes - it will leave the garbage in localStorage. Accessing a common resource from several windows simultaneously may be done by mutex based on localStorage.

I've recently published the interwindow communication library (all features are described in readme). It provides thread-safe data sharing, cross-window locks and event broadcasting. It also solves some IE issues.

Answer 2

You can communicate across tabs using localStorage. Every time you write a value, a "storage" event is fired on the window object on every tab (except the current one).

http://diveintohtml5.info/storage.html

Scroll down to "Tracking changes in the html5 storage area"

The event will include event.key, event.newValue, event.oldValue.

This only works in modern browsers.

Answer 3

You don't have control over that. The user can do basically whatever he/she wants on the computer.