How to detect if browser support offline event?

Question

I've try to use code from this question: How to detect `focusin` support?

but for chromium that spport offline event hasEvent('offline') return false. Anybody know how to detect offline/online events in JavaScript?

Answer 1

Try:

return !!window.applicationCache;

If I understand properly your question, you also may want to read this article .

EDIT:

Basically you can use the following function:

function reportConnectionEvent(e)
{
    if (!e) e = window.event;

    if ('online' == e.type) {
        alert( 'The browser is ONLINE.' );
    }
    else if ('offline' == e.type) {
        alert( 'The browser is OFFLINE.' );
    }
    else {
        alert( 'Unexpected event: ' + e.type );
    }
}
window.onload = function() {
    document.body.ononline = reportConnectionEvent;
    document.body.onoffline = reportConnectionEvent;
}  

Also you may check this for demo http://html5demos.com/offline-events

Answer 2

You can try

'onoffline' in window

or

'onoffline' in document.body

Answer 3

It seems that online and offline events start on body and bubble up so you can't use div to detect it. But I've created this code:

var body = document.getElementsByTagName('body')[0];
body.setAttribute('ononline', 'return;')
typeof body.ononline == 'function';