jQuery event triggers twice

Question

Can someone explain to me why this event triggers twice? It doesn\'t seem to do it on jQuery versions prior to 1.7.

Answer 1

From the internals, it looks like triggering blur event is triggering blur and focusout events internally which is invoking the onblur twice.

PoC

$('#box').on('blur focusout', function (e) {
    console.log('this too', e.type);
});
$('#box').blur();

Demo: Fiddle

The blur event is a non bubbling event, the bubbling counterpart is the foucsout event. So in normal circumstances the blur operation triggers both these events. So jQuery is trying to be intelligent and fires both these events in case of a blur event, but it looks like there is an bug in the implementation.