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 supports offline event hasEvent('offline') return false. Anybody know how to detect offline/online events in JavaScript?

Bud Damyanov · Answer 1 · 2014-08-13T11:27:37.207

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

I don't need to have app that work offline, I need to detect the event because I need to add ajax request to queue and when internet is back I need to send them. — jcubic, Aug 13 '14 at 11:24

score 0 · Answer 2 · answered Aug 13 '14 at 11:22

0

You can try

'onoffline' in window

or

'onoffline' in document.body

answered Aug 13 '14 at 11:22

Yury Tarabanko

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this not bulletproff check, every even check test also check if event work correctly not only if it's present. – jcubic Aug 21 '14 at 13:54
@jcubic LOL how would you check it "works correctly"? :) – Yury Tarabanko Aug 21 '14 at 14:58
And this method is widely used and robust enough for modernizr but somehow not for you (https://github.com/Modernizr/Modernizr/blob/master/src/isEventSupported.js). Kinda not cool to accept your own answers making stuff in more complex manner. – Yury Tarabanko Aug 21 '14 at 15:05
I've seen this in other SO question about events http://stackoverflow.com/questions/2877393/detecting-support-for-a-given-javascript-event where you test if the value is a function. – jcubic Aug 22 '14 at 11:48

score 0 · Accepted Answer · answered Aug 13 '14 at 11:26

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';

How to detect if browser support offline event?

3 Answers3