JSFiddle - React, Tailwind, and code Playground

HTML

<h1>isDefaultPrevented test</h1>
<p>Mouse over the following area and view the log</p>
<div id="demo">
<a href="/"><img class="x" src="http://static.flowplayer.org/tools/img/photos/1.jpg"
    title="A must have tool for designing better layouts and more intuitive user-interfaces."/></a>
<div id="log"></div>
</div>

CSS

h1
{
    font-size: 2em;
    font-weight: bold;
}
.x
{
    width: 100px;
    height: 50px;
    background: #f00;
    margin: 1em;
}

JavaScript

$('.x').bind(
    'mouseenter',
    function(e)
    {
        e.type = 'onBeforeShow';
        $(this).trigger(e, ['something']);
        $('#log').append('<p>e.isDefaultPrevented() = ' + e.isDefaultPrevented() + ', e.originalEvent.defaultPrevented = ' + e.originalEvent.defaultPrevented + '</p>');
    }
);