问题
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 send message to previously opened tab to inform that it's impossible to open 2 tabs. 2 Intependent tabs may break page offline storage and webSQL structure, so that I can't allow people to use 2 tabs. It's also semi-offline app so it needs to be client-side solution.
回答1:
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.
回答2:
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.
回答3:
You don't have control over that. The user can do basically whatever he/she wants on the computer.
来源：https://stackoverflow.com/questions/19824379/offline-cross-tab-communication-javascript-only